Implantable devices coated with extracellular matrix

ABSTRACT

Disclosed herein are medical products, including an implantable device coated with a crosslinked extracellular matrix comprising at least one of Type IV collagen and laminin, wherein the crosslinked extracellular matrix contains no more than 0.024 mg/ml total concentration of glucose, amino acids and salts having a molecular weight of 2000 daltons or less. Corresponding systems and method also are disclosed.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/828,854 filed Mar. 14, 2013, which application claims priority fromInternational Application No. PCT/US15/49718 filed Sep. 11, 2015, U.S.application Ser. No. 14/485,313 filed Sep. 12, 2014, and U.S.application Ser. No. 13/828,854 filed Mar. 14, 2013.

STATEMENT WITH REGARD TO FEDERAL SPONSORED RESEARCH & DEVELOPMENT

Some of the embodiments described herein may have been made withGovernment support under Grants awarded by the National Institute ofHealth. The Government may have certain rights in the describedembodiments.

BACKGROUND

The embodiments disclosed herein generally relate to implantable devicesand more particularly to systems and methods for improving performanceof implantable devices.

The performance and accuracy of transcutaneous and implantable sensorsis believed to be affected by biofouling, tissue reactions at or nearthe site of the sensor, and reduction of analyte access due toinflammation, blood vessel regression and fibrous encapsulation. Inaddition to causing problems with sensor function, tissue reactions andsensitivities due to the presence of transcutaneous and totallyimplantable sensors can cause discomfort to a user, and can lead toinflammation and infection.

In diabetic patients, determination and effective management of bloodglucose levels is critical to minimizing diabetes related complications.Traditionally finger sticking and external monitors coupled with insulininjections have been used to manage blood glucose levels in patientswith diabetes, but because of the need for frequent “finger sticks”,many patients with diabetes do not adequately monitor their bloodglucose levels. More recently, the development of implantable glucosesensors to continuously monitor blood glucose levels (CGM) andcontinuous insulin infusion (subcutaneous insulin infusion, SCII) havesignificantly enhanced the management of blood glucose levels inpatients with diabetes. Current glucose sensors used in CGM limits theneed for frequent blood analysis and provides significantly enhancedinsights into the dynamic nature of blood glucose changes in patientswith diabetes. Unfortunately, current commercial sensors have a limitedfunctional lifespan in vivo (3-7 days).

When CGM and SCII are combined in a single patient, but under thesupervision of the patient, it is referred to as an open loop system.When the implanted glucose sensor (i.e. CGM) controls insulin infusion(i.e. SCII) without the intervention of the patient this is referred toas a “closed loop” system or artificial pancreas. Development of anartificial pancreas (i.e. closed-loop technology) to clinically managediabetes is a major goal of the diabetes community. Recently, there havebeen an increasing number of success stories of short-term closed-loopclinical trials.

Central to the goal of the development of long-term closed looptechnology is the development of a long-term glucose sensor with highaccuracy that can effectively control insulin infusion (SCII). Becauseof questions of in vivo reliability and limited lifespan of currentcommercial sensors effectiveness in both open and closed loop systems islimited. Much of the lack of sensor performance in vivo is thought to bethe result of sensor induced inflammation, fibrosis and fibrosis-inducedvessel regression at the site of sensor implantation. It has often beenargued that the loss of blood vessels proximal to the sensor (i.e.fibrosis induced vessel regression) at the sensor implantation site is amajor cause of the loss of effective CGM in open and closed loopsystems.

Two of the major problems associated with the uses of prosthetic meshesare 1) their propensity to induce chronic inflammation and excessivefibrosis, with resulting loss of mesh pliability and mechanicalintegrity, increased stiffness at the site of the implantation, and 2)post mesh implantation infections. Frequently the result of poor meshbiocompatibility is excessive inflammation and subsequent fibrosis. Thiscan result in limited tissue mobility of the groin and abdominal walland chronic pain and loss of mobility for the patient. It is generallyaccepted that foreign body reactions (FBRs) characterized by chronicinflammation, giant cell formation, fibrosis (collagen plates) andvessel regression result in loss of mesh function via mesh contractionand mesh distortion (e.g. loss of functional pore size), as well as meshcalcification. Clearly, improving the biocompatibility of the meshimplants (i.e. decreasing inflammation and fibrosis) and meshbiostability, given the susceptibility of PET to enzymatic & hydrolyticdegradation is anticipated to result in improved mesh function bydecreasing mesh distortion, calcification and loss of mechanicalintegrity that are all too commonly associated with mesh-basedreconstructive surgeries.

In addition to biocompatibility, infection associated with meshimplantation frequently compromise mesh function and dramatically impacta patient's daily life. The timeframe for mesh related infections rangefrom 10 days post implantation (short term) up to several years postmesh implantation (long term infections). Mesh infections increase painand discomfort, hospital stay, healing/recovery time, cost, morbidity,mortality, and may require additional surgery to remove device.

It would be useful to develop products, systems and methods thatmaintain acceptable performance over longer periods of time, and thatreduce tissue reactions and sensitivities at or near the implantationsite.

SUMMARY

One embodiment disclosed herein is a surgical mesh with a layer ofdehydrated basement membrane formed thereon.

Another embodiment is a method comprising obtaining a surgical mesh,placing basement membrane in the form of a liquid or gel on the surgicalmesh, and dehydrating the basement membrane. In embodiments, thebasement membrane has cells, factors, or other additives incorporatedtherein.

Another embodiment is a method of extending the lifespan of animplantable device that is implanted in biological tissue, comprisingbonding vascular endothelial growth factor to fibronectin, adding thefibronectin to a liquid or gel comprising extracellular matrix, andcoating the implantable device with the extracellular matrix containingfibronectin and vascular endothelial growth factor.

A further embodiment is a method of promoting biocompatibility of asurgical mesh with surrounding tissue, comprising forming a coatingcomprising basement membrane comprising adenovirus vectors containingVEGF gene on the surface of the surgical mesh.

One embodiment disclosed herein is an analyte sensor having a sensingend with dehydrated basement membrane formed thereon.

Another embodiment is a method comprising obtaining a sensor, placingbasement membrane in the form of a liquid or gel on the sensor, anddehydrating the basement membrane on the sensor.

A further embodiment is a method of increasing the sensing lifespan of aglucose sensor in a mammal by at least 10 days, comprising injectingadenovirus vectors containing VEGF gene in the tissue proximate the siteof sensor tip implantation.

Another embodiment is a method of extending the lifespan of animplantable device that is implanted in biological tissue, comprisingbonding vascular endothelial growth factor to fibronectin, adding thefibronectin to a liquid or gel comprising extracellular matrix, andcoating the implantable device with the extracellular matrix containingfibronectin and vascular endothelial growth factor.

Yet another embodiment is an implantable device including at least onemember selected from the group consisting of sensors, cannulas andsurgical mesh, the device having an implantable portion with a coatingof dehydrated extracellular matrix formed thereon.

One embodiment disclosed herein is an implantable device with a layer ofdehydrated basement membrane formed thereon, the basement membrane layercomprising at least one member selected from the group consisting ofsleeve-shaped coatings for cannulas, collars for cannulas, and collarsfor sensors.

Another embodiment disclosed herein is an implantable device having acollar configured to be disposed at an interface between tissue and theimplantable device, the collar being formed from an extracellularmatrix. In embodiments, the extracellular matrix is dehydrated prior toimplantation and rehydrated after implantation.

Another embodiment is a method comprising obtaining an implantabledevice including at least one member selected from the group consistingof cannulas and sensors, placing basement membrane in the form of aliquid or gel on the cannula or sensor to form at least one of a sleeveand a collar, and dehydrating the basement membrane on the cannula orcollar. In embodiments, the basement membrane has cells, factors, orother additives incorporated therein.

A further embodiment is a method of increasing by at least 10 days thelifespan of an implantable device comprising at least one memberselected from the group consisting of cannulas and sensors inserted in amammal, comprising forming an extracellular matrix coating around aportion of the implantable device in the form of a sleeve or a collar,the coating comprising dehydrated extracellular matrix which isrehydrated after implantation, the extracellular matrix having cellsand/or factors attached thereto using fibronectin.

Another embodiment is a method of extending the lifespan of animplantable device that is implanted in biological tissue, comprisingbonding vascular endothelial growth factor to fibronectin, adding thefibronectin to a liquid or gel comprising extracellular matrix, andcoating the implantable device with the extracellular matrix containingfibronectin and vascular endothelial growth factor.

A further embodiment is a method of increasing the lifespan of animplantable device comprising at least one member selected from thegroup consisting of cannulas and sensors in a mammal, comprising forminga coating on the cannula or sensor in the shape of a sleeve and/or acollar, the coating comprising basement membrane comprising adenovirusvectors containing VEGF gene.

Yet another embodiment is analyte sensor having a sensing element and asupport element, at least one of the sensing element and support elementhaving a dehydrated modified basement membrane preparation formedthereon.

A further embodiment is a method comprising obtaining a basementmembrane preparation containing basement membrane and at least onemember selected from the group consisting of salts, glucose, individualamino acids, and vitamins and removing at least a portion of at leastone of the salts, glucose, individual amino acids and vitamins from thebasement membrane to form a modified basement membrane preparation.

The method further includes obtaining a sensor, placing the modifiedbasement membrane preparation in the form of a liquid or gel on thesensor, and dehydrating the modified basement membrane preparation onthe sensor.

Crosslinked Basement Membrane or Extracellular Matrix

An embodiment disclosed herein is an implantable device, the implantabledevice having a coating of crosslinked basement membrane formed thereon.

In embodiments, the implantable device is a sensor. In embodiments, thesensor has a sensing end, and the basement membrane is formed on thesensing end.

Another embodiment is a method comprising obtaining an implantabledevice, placing basement membrane in the form of a liquid or gel on theimplantable device, and then dehydrating and crosslinking the basementmembrane. In embodiments, the implantable device is a sensor.

Yet another embodiment is an implantable device including at least onemember selected from the group consisting of sensors, cannulas andsurgical mesh, the device having an implantable portion with a coatingof crosslinked extracellular matrix formed thereon.

Another embodiment disclosed herein is an implantable device with alayer of crosslinked basement membrane formed thereon, the basementmembrane layer comprising at least one member selected from the groupconsisting of sleeve-shaped coatings cannulas, collars for cannulas, andcollars for sensors.

Another embodiment disclosed herein is an implantable device having acollar configured to be disposed at an interface between tissue and theimplantable device, the collar being formed from an extracellularmatrix. In embodiments, the extracellular matrix is crosslinked anddehydrated prior to implantation, and rehydrated and after implantation.

Another embodiment is a method comprising obtaining an implantabledevice including at least one member selected from the group consistingof cannulas and sensors, placing basement membrane in the form of aliquid or gel on the cannula or sensor to form at least one of a sleeveand a collar, and dehydrating and crosslinking the basement membrane onthe cannula or collar. In embodiments, the basement membrane has cells,factors, or other additives incorporated therein.

A further embodiment is a method of increasing the lifespan of animplantable device comprising at least one member selected from thegroup consisting of cannulas and sensors inserted in a mammal,comprising forming crosslinked extracellular matrix coating around aportion of the implantable device in the form of a sleeve or a collar,the coating comprising dehydrated extracellular matrix which isrehydrated after implantation, the extracellular matrix having cellsand/or factors attached thereto using fibronectin. In embodiments, theimplantable device has a lifespan of at least 28 days. In embodiments,the device is a sensor, and the coated sensor is more accurate than theuncoated sensors, and more accurate than the sensors that are coatedwith non-crosslinked basement membrane, for the first day, and for thefirst seven days, of sensor use.

Yet another embodiment disclosed herein is a surgical mesh with a layerof crosslinked basement membrane formed thereon.

Another embodiment is a method comprising obtaining a surgical mesh,placing basement membrane in the form of a liquid or gel on the surgicalmesh, and crosslinking the basement membrane. In embodiments, thebasement membrane has cells, factors, or other additives incorporatedtherein.

A further embodiment is analyte sensor having a sensing element and asupport element, at least one of the sensing element and supportelements having a cross-linked basement membrane preparation formedthereon.

A further embodiment is a method comprising obtaining a basementmembrane preparation containing basement membrane and at least onemember selected from the group consisting of salts, glucose, individualamino acids, and vitamins and removing at least a portion of at leastone of the salts, glucose, individual amino acids and vitamins from thebasement membrane to form a modified basement membrane preparation. Themethod further includes obtaining a sensor, placing the modifiedbasement membrane preparation in the form of a liquid or gel on thesensor, and dehydrating and crosslinking the modified basement membranepreparation on the sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a transdermal sensor according to a first embodiment.

FIG. 2 shows a totally implantable sensor according to a secondembodiment.

FIG. 3 is a flow chart showing a method according to one embodimentdescribed herein.

FIG. 4 is a flow chart showing a method according to another embodimentdescribed herein.

FIG. 5 shows photographs of a sensor at various stages of the coatingprocess including coating, drying, re-hydrating and final drying.

FIGS. 6A-6D illustrates a method of injecting adenovirus vectorscontaining VEGF gene in accordance with a first embodiment. FIG. 6Ashows the arrangement of the mouse, sensor, commutator, potentiostat,DAS and laptop. FIG. 6B shows injection of material post sensorimplantation. FIG. 6C and FIG. 6D show the mouse post sensorimplantation.

FIGS. 7A-7P are representative example graphs for the various treatmentgroups showing continuous glucose sensing (CGS) current for a period of28 days in mice having adenovirus vectors containing mouse VEGFproximate the site of sensor implantation, as compared to three types ofcontrols. FIGS. 7A-7D show the results for four non-injected controlmice. FIGS. 7E-7H show the results for four saline injected mice. FIGS.7I-7L show the results for four mice injected with Adv-LacZ adenovirus.FIGS. 7M-7P show the results for four mice injected with Adv-VEGFaadenovirus.

FIG. 8 is a line graph showing Mean Absolute Relative Differencecalculations for the data shown in FIG. 7.

FIG. 9 is a boxplot of blood vessel density as measured by percent areaand treatment group for no injection, saline injection, Adv-LacZ andAdv-VEGFa injection.

FIG. 10 is a Table of statistical analyses of the total MARD data forall treatment groups.

FIG. 11 is a boxplot of lymphatic vessel density and blood vesseldensity as measured by percent area and treatment groups for all thetreatment groups.

FIG. 12 is a graph correlating blood vessel density and lymph vesseldensity for all treatment groups.

FIG. 13A is a table showing the relative contribution of blood vesseldensity to glucose sensor function.

FIG. 13B is a table showing a statistical comparison of lymphatic andblood vessel counts per square millimeter.

FIG. 13C is a table showing the contribution of lymph vessel density toglucose sensor function.

FIG. 13D is a table showing the contribution of both blood and lymphvessel density to glucose sensor function.

FIGS. 14A-14C are a set of photographs showing the 1) coating, 2)dehydration and 3) rehydration steps for coating a sensor with basementmembrane. FIG. 14A shows a sensor with original MATRIGEL® (reconstitutedbasement membrane) thereon. FIG. 14B shows dehydrated MATRIGEL® and FIG.14C shows rehydrated MATRIGEL®.

FIGS. 15A and 15B are graphs depicting an in vitro demonstration thatcoating glucose sensors with basement membrane does not reduce glucosesensor function when compared to non-coated sensors. FIG. 15A shows atest with no MATRIGEL® and FIG. 15B shows the results when a MATRIGEL®coating is used.

FIGS. 16A and 16B are graphs showing that basement membrane coatedsensors perform better (less variation in sensor response in nA) andlonger in vivo when compared to non-coated sensors. FIG. 16A shows atest with no MATRIGEL® and FIG. 16B shows the results when a MATRIGEL®coating is used.

FIGS. 17A-17F are photographs showing that viral vectors used in genetransfer are protected from drying induced loss of function whenencapsulated in ECM such as collagen or basement membrane when comparedto viral vectors dried without matrices. FIGS. 17A, 17C and 17E arebright field photographs showing A375 cells. FIGS. 17B, 17D and 17E showthe A375 cells when viewed under fluorescence microscopy.

FIGS. 18A and 18B are sets of photographs showing that when viralvectors are incorporated into ECM such as basement membrane that iscoated on glucose sensors, dried, and then rehydrated, the ECM protectsthe viral vectors from loss of function. FIG. 18A shows a sensor coatedwith a GFP-adenovector-MATRIGEL® coating. FIG. 18B shows a sensor coatedwith a GFP-adenovector-collagen coating.

FIGS. 19A-19D show that when using a transgenic mouse that expresseshCAR receptors (receptor for adenoviral vectors) on the surfaces ofcells, these cells can be infected with efficiency when compared to wildtype cells that lack the hCAR receptor, thus supporting the uses of hCARtransfections to enhance local gene transfer at sites of medical deviceimplantation. FIGS. 19A and 19B show spleen cells from hCAR miceinjected with GFP adenovirus. FIGS. 19C and 19D show that spleen cellsfrom control (C57BL/J) mice could not be infected.

FIGS. 20A-20F are photographs showing that transfection of normal cellswith hCAR adenovirus is not toxic to the recipient cells. Thussupporting the uses of hCAR or CAR gene therapy to enhance futureinfection by adenovirus viral vectors carrying various genes, which cancontrol tissue reactions at sites of medical device implantation. FIG.20B shows non-infected cells. FIG. 20D shows cells infected withGFP-Adv. FIG. 20F shows cells infected with GFP-Adv and then hCAR-Adv.FIGS. 20A, 20C and 20E are the brightfield controls to FIGS. 20B, 20Dand 20F respectively.

FIG. 21 is a graph showing that in vitro pretreatment of cells with hCARfollowed by subsequent infections of these cells by other viral vectors(green fluorescent protein (GFP) or hepatocyte growth factor (HGF)dramatically increases expression of GFP and HGF when compared to cellsnot pre-treated with hCAR.

FIG. 22 is a graph showing that in vitro cells pretreated with theadenoviral vector for PR-39, which selectively induce enhancedexpression of endothelial cell vascular growth factor (VEGF) expressionin human A375 cells. This PR-39 induction of VEGF would induce increasedvascular networks at sites of medical device implantation.

FIGS. 23A-23C are graphs depicting an in vitro demonstration that usinghCAR and PR-39 in combination induces a greater VEGF expression in mousefat cells then if used individually. FIG. 23A shows mVEGF expressioninduced by mVEGF-ADV in fat cells. FIG. 23B shows mVEGF expressioninduced by PR-39-ADV in fat cells. FIG. 23C shows mVEGF expressioninduced by hCAR ADV plus PR-39 ADV in fat cells.

FIG. 24 shows a list of angiogenic factors and related proteins thatcould be used as recombinant proteins or be used as genes in local genetherapy or in combination to enhance vascular networks surroundingimplanted medical devices.

FIG. 25 depicts embodiments using fibronectin as a crosslinking agentfor ECM in vitro and in vivo as well as demonstrating possible sites onthe fibronectin molecule for binding of tissue response modifiersincluding cytokines/chemokines, growth factors and inhibitors ofinflammation and fibrosis, as well as associated methods to link theseagents to the fibronectin.

FIG. 26 shows an embodiment of dry and hydrated ECM based collars andsleeves (+/−anti-microbial and or TRMs) incorporated into the ECM on aglucose sensor. FIG. 26A shows an uncoated sensor assembly. FIG. 26Bshows the sensor in tissue. FIG. 26C shows a sensor assembly thatincludes an antimicrobial collar and/or a coating containing a tissueresponse modified disposed between the collar and the sensing element.FIG. 26D shows rehydration of the collar and coating.

FIG. 27 shows an embodiment of a method for creating ECM collars andsleeves on a glucose sensor for use in implantation into a mammal.

FIG. 28 shows an embodiment incorporating anti-microbial agents andtissue response modifiers into ECM based collars and sleeves for use ona glucose sensor.

FIG. 29 shows an embodiment of tissue reactions induced by tissueresponse modifiers incorporated into ECM collars and sleeves whenimplanted into a mammal.

FIG. 30 shows an embodiment with tissue reactions induced by multipletissue response modifiers incorporated into ECM collars and sleeves whenimplanted into a mammal.

FIG. 31 shows an embodiment of a design of an extended collar for use inthe dermis and subcutaneous tissue of a transcutaneous device i.e.glucose sensor.

FIG. 32 shows an embodiment of ECM based collar for uses on a cannula orcatheter with and without incorporation of anti-microbial agents andtissue response modifiers and its use in mammalian skin.

FIG. 33 shows an embodiment of an infusion set with transcutaneouslyinserted cannula but without ECM based collars or sleeves.

FIG. 34 shows an embodiment of an infusion set with a transcutaneouslyinserted cannula with ECM based collar between cannula and skin.

FIG. 35 depicts a demonstration of methods to create a multi-ECM layeredcollar for an insulin infusion cannula using multiple coating,dehydration and rehydration steps/methods.

FIG. 36 depicts a demonstration of methods to create a multi-ECM layeredcannula sleeve for an insulin infusion cannula using multiple coating,dehydration and rehydration steps/methods.

FIG. 37 depicts a demonstration of method to create a surgical meshhaving a multi-ECM layered coating thereon that is applied usingmultiple coating, dehydration and rehydration steps/methods.

FIG. 38 is a flow chart showing one embodiment for preparing a modifiedbasement membrane preparation.

FIG. 39 shows formulations of two types of media used in making basementmembrane products sold commercially.

FIG. 40 is a set of photos showing salt crystals in dehydrated basementmembrane. FIG. 40A shows salt crystals after drying when no dialysis isused. FIG. 40B shows salt crystals after drying when a single dialysisstep is used. FIG. 40C shows a lack of salt crystals after drying whentwo dialysis steps are used.

FIG. 41 includes photos showing the effect of pre-dialyzed andpost-dialyzed basement membrane on tissue surrounding implanted sensors.FIGS. 41A and 41B show pre-dialysis basement membrane at 10× and 20×magnification, respectively. FIGS. 41C and 41D show post-dialysisbasement membrane at 10× and 20× magnification, respectively.

FIG. 42 schematically shows an implant with a coating formed fromcrosslinked basement membrane.

FIG. 43 schematically shows an implant with a multi-layer coating inwhich the inner layer is formed from crosslinked basement membrane andthe outer layer is formed from basement membrane that is notcrosslinked.

FIG. 44 schematically shows an implant with a multi-layer coating inwhich the inner layer is formed from a drug release system and the outerlayer is formed from crosslinked basement membrane.

FIG. 45 schematically shows an implant with a multi-layer coating inwhich the inner layer is formed form a drug release system, theintermediate layer is formed from crosslinked basement membrane, and theouter layer is formed from basement membrane that is not crosslinked.

FIG. 46 schematically shows an implant with a coating formed fromcrosslinked basement membrane, in which the crosslinked basementmembrane supports one or more factors, natural fibers, and/or syntheticfibers.

FIG. 47 illustrates a process for dehydrating and crosslinking basementmembrane on an implantable device. FIGS. 47A-47C show mounting of aglucose sensor and application of dialyzed basement membrane. FIG. 47Dshows the dried basement membrane on the sensor. FIGS. 47E and 47F showapplication of dialyzed basement membrane to the other side of thesensor, followed by drying. FIG. 47G, FIG. 47H and FIG. 47I show removalof the sensor from the liner, dipping and drying. FIG. 47J, FIG. 47K andFIG. 47L showing dipping and drying of the coated sensor.

FIG. 48 is a graph showing average mean MARD over time for sensorscoated with crosslinked basement membrane and sensors coated withbasement membrane that is not crosslinked.

FIG. 49 is a graph showing average mean MARD over time for sensorscoated with crosslinked basement membrane, sensors coated with basementmembrane that is not crosslinked, and uncoated control sensors duringthe first 7 days post sensor implantation in a mouse model of continuousglucose monitoring (CGM).

FIG. 50 is a set of histo-pathologic photomicrographs showing samplesfrom Example 16 at 7 days post implant, 14 days post implant, 21 dayspost implant and 28 days post implant. FIG. 50A, FIG. 50B, FIG. 50C andFIG. 50D show uncoated sensors.

FIG. 50E, FIG. 50F, FIG. 50G and FIG. 50H show sensors coated withnon-crosslinked basement membrane. FIG. 50I, FIG. 50J, FIG. 50K and FIG.50L show sensors coated with crosslinked basement membrane at 20×magnification. FIG. 50M, FIG. 50N, FIG. 50O and FIG. 50P show sensorscoated with crosslinked basement membrane at 40× magnification. FIG.50Q, FIG. 50R, FIG. 50S and FIG. 50T show sensors coated withcrosslinked basement membrane at 10× magnification.

FIG. 51 is a set of immuno-histologic photomicrographs showing thepresence and distribution of macrophages at the site of glucose sensorimplantation. FIG. 51A, FIG. 51B, FIG. 51C and FIG. 51D show uncoatedsensors. FIG. 51E and FIG. 51F show sensors coated with uncrosslinkedbasement membrane. FIG. 51G and FIG. 51H show sensors coated withcrosslinked basement membrane.

FIG. 52 is a table showing mean MARD data for statistical analysis ofMean Mards sensor performance between different test groups. The valuesin the individual boxes are p values for statistical significancebetween each comparison at 7, 14, 21 and 28 days post sensorimplantation.

FIG. 53 is a table showing total MARD data for comparison of statisticalsignificance between the selected groups of mice implanted with glucosesensors.

FIG. 54 is a photomicrograph showing vessel formation after a 2 monthterm of sensor implantation.

DETAILED DESCRIPTION

Based on work described herein, the applicant believes that bothfibrosis itself and fibrosis-induced vessel regression worksynergistically to limit effective CGM in vivo. Specifically, fibrosisnot only induces blood vessel regression at sites of sensor implantationbut fibrosis is also known to slow glucose diffusion between the bloodvessel and the implanted glucose sensor. This fibrosis based inhibitionof glucose diffusion results in the loss of “real time” blood glucosemeasurements because of the element of time delay.

In the past, efforts to overcome fibrosis and vessel regression ininjured tissues such as ischemic hearts and limbs have focused on theuses of recombinant angiogenic factors (AF) and genes (e.g. VEGF) toinduce tissue regeneration. Although local delivery of recombinant AFsuch as VEGF can cause neovascularization of the tissue, the ceasing ofAF delivery generally results in vessel regression and loss of tissueviability. This limitation of recombinant AF has spurred efforts toutilize local AF gene therapy to create and sustain vascular networks atsites of tissue injury and ischemia. Although there has been significantdiscussion related to the importance of neovascularization in sensorfunction, in actuality there have only been limited sensor studies todemonstrate its effect. In all the cases known to the applicant, theissue of vessel regression with the ceasing of VEGF delivery remains amajor problem with this approach.

Embodiments described herein utilize a murine model of CGM andadenovirus based local gene therapy over a 28 day time period, and showthat local gene therapy using VEGFa adenoviruses can induce significantangiogenesis and neovascularization at senor implantation sites andthereby significantly extend glucose sensor life spans in vivo.

A new and effective way of applying coatings to sensors is alsodescribed herein. In the past, biological coatings were applied inliquid or gel form at the time they were to be used. In embodimentsdescribed herein, one or more coatings are applied to the sensors andthen dehydrated. The sensors can then be packaged in sterile packagingfor shipping. The sensors are implanted with dehydrated coatings presentthereon. The coatings will become rehydrated due to the presence ofliquid in the surrounding tissue after they have been implanted.

In embodiments, a final hydration step is added before implantation toremove salts that have accumulated as a result of the multiplelayering/coating of the sensor. This high salt might be toxic if thecoated implantable device was implanted directly into the tissue (saltcomes, for example, from the MATRIGEL® buffers, which are important tostabilize the MATRIGEL® in its liquid form).

Additionally, this rehydration step can also be used to incorporateadditional factors into the MATRIGEL® such as angiogenic factors, drugs,antimicrobials. This can be important if the factors tend to be libel(be effected by temperature or repeated drying).

Definitions:

The general meaning of the following terms as used in the presentapplication, unless specifically modified, are: “Normal Cells”:biological cells derived from living organisms, and/or tissues, whichretain a normal genotype and phenotype, usually obtained directly fromtissue or from primary culture. “Mutant Cells”: biological cells withspontaneously altered genotype and phenotype, such as cancer cells, cellderived from naturally occurring genetically deficient organisms,usually obtained in secondary culture and or continuous cell lines.“Engineered Cells”: genetically or chemically modified biological cells(usual original source is Normal or Mutant cells). “Transgenic Cells”:biological cells derived from transgenic animals, in which the cellshave genetically induced alterations of genotype and or phenotype. “GeneTransfer Cells”: biological cells that have altered phenotype resultingin alteration of cell structure and or function. This includesknockouts, knockdowns, “over-expressors” etc. “Chemically ModifiedCells”: biological cells in which membrane, cytoplasm structural orenucleolar elements of the cell are altered permanently or for extendedperiods, thus altering cell structure and or function. “ArtificialCells”: biological cells lacking the ability to replicate but capable ofsensing and responding to their microenvironment. For example enucleatedcells, or cells lacking a nucleus (e.g. red blood cells), in whichgenetic elements such as DNA, RNA, viral vectors, nanodevices ornanomaterials can be incorporated for in vivo uses. “Hybrid Cells”:biological cells that are the result of cells fusion, and orcombinations of engineered and or artificial cells. “Matrix material”:complex heterogeneous networks of insoluble macromolecules such asglycoproteins, carbohydrates, structural proteins (e.g. collagen), aswell as bound proteins and factors. These matrices contain specificbinding sites for cells, factors (e.g. cytokines and growth factors) andproteins, which directly control cell adhesion and function in vivo andin vitro. “Biological Matrices”: matrices obtained from organisms,tissues, or cell. Examples of biological matrices include interstitialmatrices, basement membrane, fibrin clots. Interstitial matrices aregenerally composed of fibrillar and nonfibrillar collagen, elastin,fibronectin proteoglycans, hyuronate, as well as other components.Basement membranes are composed of nonfibrillar collagen (usually IV),laminin, heparin sulfate, proteoglycan, and other glycoproteins. Fibrinclots are complex networks of plasma proteins including fibrin(ogen),fibronectin, glycoproteins, heparin, thrombin collagen, as well as otherplasma proteins cross-linked to the fibrin clots via Factor XIII.Additionally, fibrin clots have extensive binding sites for variousfactors and cells including leukocytes, fibroblasts and endothelialcells. “Engineered Matrices”: genetically and or chemically modifiedbiological matrices. “Hybrid matrices”: combinations of biological,engineered and or artificial matrices. In addition, the meaning ofvarious abbreviations as used within the present application, unlessspecifically modified, include ES, embryonic stem cell; MSC, mesenchymalstem cell; MAPC, multipotent adult progenitor cell; HSC, hematopoieticstem cell; NSC, neural stem cell; NPC, neural progenitor cell; MDSC,muscle-derived stem cell; ECM, extracellular matrix; EGF, epidermalgrowth factor; LIF, leukemia inhibitory factor; SCF, stem cell factor;HGF, hepatocyte growth factor; PDGF, platelet-derived growth factor;VEGF, vascular endothelial growth factor; BMP, bone morphogeneticprotein; BDNF, brain-derived neurotrophic factor; NT, neurotrophin;CNTF, ciliary neurotrophic factor; bFGF, basic fibroblast growth factor;TGF-ß, transforming growth factor-beta; IL, interleukin; G-CSF,granulocyte-colony stimulating factor; GM-CSF, granulocyte-macrophagecolony stimulating factor; IGF, insulin-like growth factor; RA, retinoicacid; and FBS, fetal bovine serum.

As used herein, “extracellular matrix” (ECM) means biological matricesproduced by cells, which can create 3D complexes. Examples include,basement membranes, collagens, fibrin etc. As used herein, “artificialtissue system (ATS)” is a combination of extracellular matrices as wellas other additives and cells that can be coated on the surface of animplantable device to enhance the biocompatibility of the device and itsperformance. “Sensor response” is the raw output in nano-amperes (nA) ofa sensor in vivo or in vitro. “Loss of sensor response” is defined asnot correlating with previously measured glucose values, e.g. when thesame glucose level is present while at the same time the output in nAconsistently falls over time, or when glucose levels increase but thesensor does not detect this increase. “Loss of sensor function” as usedherein refers to a fall in sensor output (nA) over time with anon-changing glucose level.

In the context of glucose sensors, “sensor sensitivity” is measured asnano-Amps per milli-mole of glucose or nano-Amps per mg of analyte (suchas glucose) per deciliter. The mM glucose or dL glucose level is derivedfrom an external meter, using blood from a finger prick, to make theglucose determination. The sensor output and external monitormeasurements are made at the same time. Loss of sensor sensitivity canbe expressed as the ratio between the change in sensor response in nAdivided by the change in blood analyte concentration in mM. See Klueh U,Kreutzer, D, “Murine model of implantable glucose sensors: a novel modelfor glucose sensor development,” Diabetes Technol. Ther. 2005,7:727-737, the contents of which are incorporated by reference herein intheir entirety.

“Sensor lifespan” refers to the time, in days or hours, that sensoroutput and sensitivity are adequate to allow detection of whether or notthe analyte levels in an organism are acceptable. In a glucose sensor,the lifespan is a time that sensor output is adequate to detect whetherblood glucose levels are normal glycemic, hypoglycemic, orhyperglycemic.

As used herein, “dehydrated biological matrix” refers to dried, solidbiological matrix. “Dehydrated basement membrane” refers to dried, solidbasement membrane.

As used herein, “cell culture derived basement membrane” refers tobasement membrane, which is extracted (solubilized) from in vitro cellcultures containing mammalian cells. As used herein, “tissue derivedbasement membrane” refers to basement membrane, which isisolated/extracted from animal tissues such as intestines. As usedherein “solubilized basement membrane” means any soluble basementmembrane obtained from cells in culture or mammalian tissue. As usedherein, “liquid basement membrane” refers to basement membrane which isfluid basement membrane which exists in many cases at temperatures at 4°C. or below whereas gel basement membrane will start to form above 10Deg. C and will gel rapidly at 22-35 Deg. C.

As used herein, “lymphangiogenesis” refers to the formation of newlymphatic vessels. “Angiogenesis” refers to the formation of new bloodvessels.

As used herein, “viral gene therapy” refers to the insertion ofgene-containing viruses into a host. The virus produces a continuingsupply of the gene product. “Recombinant protein” are proteins that arenormally produced in vitro and then purified and then subsequentlyinjected or delivered to a host tissue or vascular.

As used herein “cannula”, refers to an elongated tube configured fordelivery of a liquid, such as saline or a pharmaceutical product. Acatheter is a type of a cannula. As used herein, “collar” refers to athree dimensional, annular device configured to surround an elongatedcannula, sensor, or other device to the surface of tissue such as skintissue. The collar usually is positioned between the device and the skinlayer.

As used herein, “modified basement membrane preparation” means abasement membrane solution or gel from which the small molecular weightcomponents have been removed, including but not necessarily limited tosalts, glucose, individual amino acids and vitamins. “Modifiedextracellular matrix preparation” as used herein means an extracellularmatrix solution or gel from which the small molecular weight componentshave been removed, including but not necessarily limited to salts,glucose, individual amino acids and vitamins.

As used herein, “crosslinked basement membrane” means a basementmembrane in the form of a gel or solid in which the basement membrane iscrosslinked with a crosslinking agent that induces covalent bondingwithin the basement membrane preparations. In embodiments, thecrosslinking agent is biocompatible at the concentrations in which it isused.

List of a First Set of Product Embodiments Described Herein

-   -   1. In one embodiment, the coated sensor, which has not yet been        inserted in a user, has an outer coating of dehydrated        extracellular matrix (ECM) formed thereon, such as basement        membrane.    -   2. In another embodiment, the coated sensor, which has not yet        been inserted into a user, has a coating of dehydrated basement        membrane formed therein, with additives incorporated therein        (protein and non-protein substances such as factors (drug),        cytokines, and antibodies).    -   3. In another embodiment, the coated sensor has multilayer        coatings, including a first coating of an extracellular matrix        followed by a second coating of the same or a different        extracellular matrix.    -   4. In another embodiment, the ECM coated sensors, which is a        transdermal or totally implantable sensor, has been implanted        and the basement membrane has been rehydrated in the tissue        following implantation. In embodiments, the body's own fluids        rehydrate the membrane.    -   5. In yet another embodiment, a system (kit) that includes at        least one extracellular matrix, a device to apply the ECM to the        implant and a protocol for using the kit to coat the implant        with at least one layer of ECM as well as a specific drying and        hydrating method described.        A First Set of Disclosed Method Embodiments

In yet another embodiment, a method of making (coating) a sensor isdescribed in which basement membrane in the form of a liquid or gel isapplied to a sensor and dehydrated at ambient temperature. The basementmembrane is later rehydrated before or after the sensor is inserted in auser.

In a further embodiment, the method of making a sensor is described inwhich basement membrane in the form of a liquid is applied to a sensorat 4° C. and dehydrated at a temperature in the range of 4Deg. C. Thebasement membrane is later rehydrated after the sensor is inserted in auser.

Another embodiment is a method of making a sensor in which a coating isapplied, before as a coating or “insertion pocket” and/or afterinsertion in a user, which promotes lymphangiogenesis. The coatingcomprises at least one extracellular matrix and at leastlymphangiogenesis factor such as VEGF-C.

List of a Second Set of Product Embodiments Described Herein

-   -   1. In one embodiment, the coated cannula, which has not yet been        inserted in a user, has an outer coating of dehydrated basement        membrane.    -   2. In another embodiment, the coated cannula, which has not yet        been inserted into a user, has a coating of dehydrated basement        membrane formed therein, with additives incorporated therein        (protein and non-protein substances such as factors (drug),        cytokines, antibodies).    -   3. In another embodiment, the coated cannula has multilayer        coatings, including a first coating of an extracellular matrix        followed by a second coating of the same or a different        extracellular matrix.    -   4. In another embodiment, the ECM coated cannulas, which may be        affiliated with a transcutaneous or totally implantable sensor,        has been implanted and the basement membrane has been rehydrated        in the tissue following implantation.    -   5. In a further embodiment, a collar for a sensor or other        implantable device is itself made out of extracellular matrix        material such as basement membrane.

The collar may be formed of one layer, or multiple layers. Multi-layercollars can have layers that are formed from different ECMs and/orcontain different additives.

-   -   6. In yet another embodiment, a system (kit) that includes at        least one extracellular matrix, a device to apply the ECM to the        implant and a protocol for using the kit to coat the implant        with at least one layer of ECM as well as a specific drying and        hydrating method described.    -   7. Cannulas used herein can be employed in conjunction with an        infusion device, such as an insulin pump. An infusion pump        infuses fluids, medication or nutrients into a patient's        circulatory system. It is generally used in subcutaneous,        intravenously, arterial and epidural infusions        A Second Set of Disclosed Method Embodiments

In yet another embodiment, a method of making (coating) a cannula isdescribed in which basement membrane in the form of a liquid or gel isapplied to a cannula and dehydrated at ambient temperature. The basementmembrane is later rehydrated before or after the cannula is inserted ina user.

In a further embodiment, the method of making a cannula or collar isdescribed in which basement membrane in the form of a liquid is appliedto a sensor at 4° C. and dehydrated at a temperature in the range of4[[C]] Deg. C. The basement membrane is later rehydrated after thecannula or collar is inserted in a user.

Another embodiment is a method of making a cannula or collar in which acoating is applied, before as a coating or “insertion pocket” and/orafter insertion of the cannula or collar in a user, which promoteslymphangiogenesis. The coating comprises at least one extracellularmatrix and at least lymphangiogenesis factor such as VEGF-C.

List of a Third Set of Product Embodiments Described Herein

-   -   8. In one embodiment, the coated cannula, which has not yet been        inserted in a user, has an outer coating of dehydrated basement        membrane.    -   9. In another embodiment, the coated cannula, which has not yet        been inserted into a user, has a coating of dehydrated basement        membrane formed therein, with additives incorporated therein        (protein and non-protein substances such as factors (drug),        cytokines, antibodies).    -   10. In another embodiment, the coated cannula has multilayer        coatings, including a first coating of an extracellular matrix        followed by a second coating of the same or a different        extracellular matrix.    -   11. In another embodiment, the ECM coated cannulas, which may be        affiliated with a transcutaneous or totally implantable sensor,        has been implanted and the basement membrane has been rehydrated        in the tissue following implantation.    -   12. In a further embodiment, a collar for a sensor or other        implantable device is itself made out of extracellular matrix        material such as basement membrane. The collar may be formed of        one layer, or multiple layers. Multi-layer collars can have        layers that are formed from different ECMs and/or contain        different additives.    -   13. In yet another embodiment, a system (kit) that includes at        least one extracellular matrix, a device to apply the ECM to the        implant and a protocol for using the kit to coat the implant        with at least one layer of ECM as well as a specific drying and        hydrating method described.    -   14. Cannulas used herein can be employed in conjunction with an        infusion device, such as an insulin pump. An infusion pump        infuses fluids, medication or nutrients into a patient's        circulatory system. It is generally used in subcutaneous,        intravenously, arterial and epidural infusions.    -   15. In a further embodiment, a surgical mesh is coated with one        or more layers of ECM, with the mesh being dehydrated after each        layer is applied. Additives can be incorporated into the ECM,        including protein and non-protein substances such as factors        (drug), cytokines, antibodies.        A Third Set of Disclosed Method Embodiments

In yet another embodiment, a method of making (coating) a cannula isdescribed in which basement membrane in the form of a liquid or gel isapplied to a cannula and dehydrated at ambient temperature. The basementmembrane is later rehydrated before or after the cannula is inserted ina user.

In a further embodiment, the method of making a cannula or collar isdescribed in which basement membrane in the form of a liquid is appliedto a sensor at 4° C. and dehydrated at a temperature in the range of4[[C]] Deg. C. The basement membrane is later rehydrated after thecannula or collar is inserted in a user.

Another embodiment is a method of making a cannula or collar in which acoating is applied before as a coating or “insertion pocket” and/orafter insertion of the cannula or collar in a user, which promoteslymphangiogenesis. The coating comprises at least one extracellularmatrix and at least lymphangiogenesis factor such as VEGF-C.

A further embodiment is a method of making a surgical mesh comprisingcoating the mesh with one or more layers of ECM, with or without theincorporation of additive in the ECM.

System Components

The components of the systems described herein include ImplantableDevices, Matrix Material, and in some cases, Cells and Factors, etc.inserted into the matrix. Each of these components is described below.In FIG. 1, the sensor system 8 includes a sensor 10 and a tissue system12 that includes a matrix material 22 and optionally includes cellsand/or factors supported in the matrix material 22. In FIG. 2, thesensor system 8′ includes a sensor 10′ and a tissue system 12′ thatincludes a matrix material 22′ and optionally includes cells and/orfactors supported in the matrix material 22′.

Types of Implantable Devices

The collars can be used in conjunction with implantable sensors, as wellas other implants that have an elongated, thin configuration.Transcutaneous and fully implantable sensors can be used in theembodiments described herein. A transcutaneous sensor is shown in FIG. 1and a fully implantable sensor is shown in FIG. 2. The sensors may bechemical sensor and/or biosensors. Glucose sensors, includingamperometric glucose sensors, for example, glucose oxidase sensors,fluorescence based glucose sensor can be used. Other types of sensorsincluded herein are implantable sensors for monitoring conditions suchas blood pH, ion concentration, metabolite levels, clinical chemistryanalyses, oxygen concentration, carbon dioxide concentration, andpressure. It should be understood that the implant devices may becomeembedded, or otherwise integrated, into the biological system.

Sensors typically are made from the following materials: metals,including silver and platinum, and coatings which typically arethermoplastics and thermosets, including polyurethane andpolytetrafluoroethylene, and composites. A non-limiting example of acommercially used sensor coating is a high-molecular-weight poly(vinylpyridine)-poly(ethylene glycol) copolymer cross-linked using atrifunctional short chain epoxide. Particular materials used in implantsof various types are nylon, for example Nafion®, which is a sulfonatedtetrafluoroethylene based fluoropolymer-co-polymer, and silicone, whichhas frequently been used in implants and generally has minimalreactivity in mammalian tissues. Reactivity of nylon and siliconematerials was evaluated in the ex ova chicken model, as is described inU.S. application Ser. No. 10/578,171, the contents of which areincorporated herein by reference in their entirety. PTFE materials suchas Teflon have been used in sensors, often as a coating for a metal wire(see US application Ser. No. 10/578,171).

In embodiments, other devices may be used in addition to the sensor 10,or may replace the sensor 10. For example: bioreactors for liver, kidneyor other organ support systems; catheters; artificial arteries;artificial organs; tissue fragment-containing devices; cell-containingdevices; ligament replacements; bone replacements; coronary pacemakers;lap-bands, monitors; artificial larynxes; prostheses; brain stimulators;bladder pacemakers; shunts; stents; tubes; defibrillators;cardioverters; heart valves; joint replacements; fixation devices;ocular implants; cochlear implants; breast implants; neurostimulators;bone growth stimulators; vascular grafts; muscle stimulators; leftventricular assist devices; pressure sensors; vagus nerve stimulators;drug delivery systems; sutures and staples. In addition the devices mayinclude implants. For example: prostheses, such as joint replacements;artificial tendons and ligaments; dental implants; blood vesselprostheses; heart valves; cochlear replacements; intraocular lens;mammary prostheses; penile and testicular prostheses; tracheal,laryngeal, and esophageal replacement devices; artificial organs such asheart, liver, pancreas, kidney, and parathyroid; repair materials anddevices such as bone cements, bone defect repairs, bone plates forfracture fixation; heart valves; catheters; nerve regeneration channels;corneal bandages; skin repair templates; scaffolds for tissue repair andregeneration including surgical meshes; and devices such as pacemakers,implantable drug delivery systems (e.g., for drugs, human growthhormone, insulin, bone growth factors, and other hormones). Furthermore,the device may include implantable drug delivery systems such as thosedisclosed in U.S. Pat. Nos. 3,773,919, 4,155,992, 4,379,138, 4,130,639,4,900,556, 4,186,189, 5,593,697, and 5,342,622 which are incorporated intheir entirety by reference herein. Implantable sensors for monitoringconditions such as blood pH, ion concentration, metabolite levels,clinical chemistry analyses, oxygen concentration, carbon dioxideconcentration, pressure, and glucose levels are known. Blood glucoselevels, for example, may be monitored using optical sensors andelectrochemical sensors. It should be understood that the implantdevices may become embedded, or otherwise integrated, into thebiological system.

Cannulas described herein can be employed in conjunction with aninfusions device, such as an insulin pump. These cannulas and cathetersare made of a variety of materials plastics and metals and are used toinfuse drugs, liquids such as saline, nutrients, antibiotics.

Surgical meshes described herein can be made from a variety ofbiocompatible materials, including but not limited to cellulose,polypropylene, polyesters, and polyethylene terephthalate (PET).Surgical meshes can also be produced from acellularized human or animaltissues.

FIG. 26C-26D show a sensor assembly with a collar. The sensor assembly400 includes electronics 402, a sensing element support 404 with asensing element 406 at the tip. The sensing element support 406 has anantimicrobial collar 408 configured to be positioned on both sides ofthe point at which the support enters the tissue 410. A coating 412containing a tissue response modifier, such as those described above isdisposed between the collar 408 and the sensing element 406. Thisconfiguration prevents inflammation that otherwise may occur, as shownin FIG. 26B, within the tissue around the sensor and support. While thecoating 412 usually is rehydrated after implantation to minimizediscomfort to the patient, the coating 412 also can be rehydrated beforeimplantation. In embodiments, the coating can be applied immediatelybefore assembly, in which case initial dehydration would not berequired.

In embodiments, the implantable device is a surgical mesh of the typeused for reconstructive surgery, such as hernia repair.

Matrix Material

Referring to FIGS. 1-2, the artificial tissue system (ATS) 12 furtherincludes a matrix material 22. The matrix material 22 may be naturaland/or synthetic materials. For example, the matrix material 22 mayinclude biological matrices, such as naturally occurring matrices thatoccur in viable organisms (in vivo), and tissues including ex vivotissues, as well as in association with cells maintained in vitro, orcombinations thereof. One characteristic of the matrix material 22 isthe ability to provide a three dimensional structure to the ATS 12. Thisthree dimensional structure provides a volume of space that allows forbiological contact wherein various components of the ATS 12, sensor 10,and surrounding tissues can biologically associate with one another. Forexample, the matrix material may provide the necessary framework inwhich various cells can be secured as well as providing for the movementof nutrients, chemicals, and other bioactive agents to, from, and/orbetween cells, tissues, and/or an implant device, such as, the sensor10. In addition, the matrix material 22 is in biological contact withportions of the implant device and the surrounding biological system, ifpresent. It should be understood that the biological contact includes,among other things, chemical, liquid, gas, and/or mechanical contact.For example, cellular tissue of the biological system may intrude, orotherwise extend physically into the volume of space occupied by thematrix material. This cellular tissue may also be in physical, chemical,and/or fluid contact with the cells, portions of the implant device,such as the sensor 10, genetic elements 16, cell response modifiers(CRM) 18, and/or tissue response modifiers (TRM) 20. The geneticelements 16 include, for example, agent(s) that directly cause thetemporary or permanent change of the genetic composition or expressionof a cell or tissue, or indirectly cause the temporary or permanentchange of the genetic composition or expression of a cell or tissue. Forexample, single or double strand DNA, single or double strand RNA,plasmids, viral vectors, and/or DNA or RNA viral vectors. In addition,it should be understood that the ATS may be formed into, for example,any biologically relevant shape, for example, a tube, sponge, sphere,strand, coiled strand, capillary network, film, fiber, mesh, and/orsheet.

In one embodiment, the matrix material 22 may include: basementmembranes, for example MATRIGEL®; fibrin clots, including plasma derivedclots; collagens, for example, fibrillar collagens (types I, II, III, Vand IX collagen); basement membrane collagen, such as type IV collagen;other collagens (types VI, VII, IX, XVII, XV and XVIII collagen);fibronectin; laminin; proteoglycans; glycoproteins; glycoaminoglycans;elastins; hyaluronan; adhesive glycoproteins; mucins; andpolysaccharides. In some cases, certain factors can be included with thematrix material 22 to advantageously enhance the characteristics of thematrix material 22 and/or its production. For example, factors that canbe included are: TGF-beta; FGF; angiotensin II; Insulin-like growthfactor; and ascorbic acid.

In one embodiment, the matrix material 22 is composed of a solubilizedbasement membrane preparation such as MATRIGEL® as supplied from BDBiosciences. The solubilized basement membrane, like fibrin, is anaturally occurring protein matrix/bio-hydrogel, that has a wide varietyof binding sites for cells and factors. These factors may include growthfactors and cytokines. For example, the solubilized basement membranemay include laminin, collagen, including collagen IV, heparin sulphateproteoglycans, and entactin. Solubilized basement membrane has been usedextensively as a cell matrix/depot in a wide variety of in vitro and invivo studies particularly in the area of tumor cell biology andangiogenesis.

In one embodiment the solubilized basement membrane is a liquid at 4° C.but becomes a solid bio-hydrogel when warmed to 37° C. (or less). Thisability to convert solubilized basement membrane from a liquid to asolid by simply raising the temperature, allows for a wide variety ofstrategies for entrapping genetically engineered cells, factors,proteins and genes. It should be understood that the terms entrap,entraps, entrapped, entrapping, and the like are intended to include forthe purpose of this application the concept that the matrix material 22provides a mechanical association with the biological cells and/or thatthe matrix material 22 provides specific binding sites for thebiological cells. For example, specific binding sites which includereceptor and/or adhesion sites.

As previously discussed, MATRIGEL® is an isolated basement membraneobtained for cells cultured in vitro, which has been used in a widevariety of in vivo and in vitro studies of cell attachment, cell growthand angiogenesis. Like fibrin, MATRIGEL® is a naturally occurring matrixderived from basement membrane, that has a wide variety of binding sitesfor cells and factors (including growth factors and cytokines).MATRIGEL® has been used extensively as a cell matrix/depot in a widevariety of in vitro and in vivo studies particularly in the area oftumor cell biology and angiogenesis. MATRIGEL® is a liquid at 4° C. butbecomes a solid biological matrix when warmed to 37° C. This ability toconvert MATRIGEL® from a liquid to a solid by simply raising thetemperature, allows for a wide variety of strategies for entrappinggenetically engineered cells, factors proteins and genes. MATRIGEL® andother isolated basement membrane materials possess the characteristicsto serve as a tissue interactive biological matrix for the ATS.

According to the literature, basement membrane contains laminin, type IVcollagen, and a heparin sulfate proteoglycan (perlecan). BD MATRIGEL®Matrix is a reconstituted basement membrane preparation that isextracted from the Engelbreth-Holm-Sawrm (EHS) mouse sarcoma, a tumorrich in extracellular matrix proteins (extracted from cell cultures invitro). Once isolated, the material has approximately 56-61%, or 60%,laminin, 30-31% collagen IV and 7-8% entactin. MATRIGEL® matrix alsocontains heparin sulfate proteoglycan, TGF-Beta, epidermal growthfactor, insulin-like growth factor, fibroblast growth factor and tissueplasminogen activator. The growth factors occur naturally in the EHStumor. When frozen, MATRIGEL® matrix is a solid. When allowed to thaw ina refrigerator (4° C.) and when stored in a refrigerator, MATRIGEL®matrix is a liquid. MATRIGEL® matrix will start to form a gel above 10Deg. C and will gel rapidly at 22-35 Deg. C. MATRIGEL® matrix will forma gel if it is diluted up to a concentration of 3 mg/ml.

In embodiments, the basement membrane is crosslinked with crosslinkingagent that forms covalent bonds between components of the basementmembrane and is biocompatible with the surrounding tissue in the amountin which it is used. In embodiments, the crosslinking agent comprises adi-aldehyde.

When the crosslinking agent is glutaraldehyde, it typically is used inquantities of 0.1-1% W/W, or 0.1-0.6% W/W, or 0.2-0.2% W/W. Inembodiments, when the implantable device is placed in a liquidglutaraldehyde solution, the exposure time ranges from 3 to 10 minutes.

Cells, Genetic Elements, Cell Response Modifiers, Tissue ResponseModifiers, Genetic Elements and Factors

When cells are incorporated into the basement membrane, the cells caninclude biological cells 14, 14′, genetically engineered cells 14 a, 14a′, artificial cells 14 b, 14 b′, stem cells 14 c, 14 c′, and/or supportcells 14 d, 14 d′. The support cells 14 d, 14 d′ generally are includedwith other cells and serve to provide nutrients, factors, physicalsurfaces, or other required or desirable products to the cells theysupport. The ATS may also include genetic elements 16, 16′, cellresponse modifiers (CRM) 18, 18′, and/or tissue response modifiers (TRM)20, 20′.

In one embodiment, the cells include eukaryotic cells; prokaryoticcells; vertebrates cells; invertebrates cells; normal cells; cancercells; mutant cells; engineered cells, such as genetically alteredcells, chemically altered cells, transgenic cells, hybrid cells(hybridomas); artificial cells; and stem cells, such as embryonic stemcells, adult stem cells, stem cell lines, engineered stem cells. Thecells may be classified as categories of functional cells, for example,inflammatory cells, immune cells, tissue cells, cells which controlwound healing, cells which control fibrosis, cells which control tissueregeneration, regulatory cells, cytokine producing cells, growth factorproducing cells, matrix producing cells, vascular cells, connectivetissue cells, bone producing cells and bone, blood cells. The cells mayalso be classified as types of cells, for example, endothelial cells,fibroblasts, epithelial cells, muscle cells, fat cells, lymphocytes,macrophages, mast cells, polymorphonuclear leukocytes, red blood cells,neurologic cells, osteoblasts, osteoclasts, nerve cells, fat cells,brain cells. Other categories of cells may be used and include, but arenot limited to, autologous cells, heterologous cells, allogenic cells,xenogenic cells, autologous cells, (relative to the host), heterologouscells (relative to the host), allogenic cells (relative to the hosttissue), xenogenic cells (relative to the host tissue). It should beunderstood that the cells may be used in combination with one anothersuch that a cellular component is formed. The cellular component mayinclude one or more cellular communities wherein the communitiesinteract on, for example, symbiotic, commensal, saprophytic, inhibitoryand/or other biologically relevant association. For example, engineeredand non-engineered cells may be used in combination to provideadvantageous biologic contact with one another and with a biologicsystem with which they are associated, for example a living mammalbiologic system.

In one embodiment, cell of different categories and/or types may becombined in the matrix material 22. For example, functional cells may beused which regulate the function of other cells within the matrixmaterial 22. This may include cells that produce cytokines and growthfactors; cells that regulate the function of the cells within the hosttissue; cells that include matrix producing cells within the hosttissue; cells that produce cytokines and growth factors which controlcells in the host tissues; cells that controls inflammation within theATS; cells that control wound healing within the ATS; cells that controlfibrosis within the ATS; cells that control neovascularization withinthe ATS; cells that control cell proliferation within the ATS; cellsthat control immune responses within the ATS; cells that include cellsthat control cell death within the ATS; cells that includes cells thatcontrol inflammation within the tissues; cells that control woundhealing within the tissues; cells that control fibrosis within thetissues; cells that control neovascularization within the tissues; cellsthat control cell proliferation within the tissues; cells that controlimmune responses within the tissues; cells that control cell deathwithin the tissues; cells that produces cytokines; cells that producegrowth factors; cells that control vessel formation and regression;cells that produce genetically altered proteins and peptides; and cellsthat overproduce proteins and/or peptides.

Sources of biological cells include cells directly isolated from in vivosources; cells obtained from embryonic tissues, neonatal tissues,juvenile or adult tissues; cells obtained from in vitro sources; cellsobtained from primary cell culture sources; cells obtained fromsecondary cell culture sources; and cells obtained from continuous celllines.

In one embodiment, the CRM 18 and/or TRM 20 are differentiated based ontheir biologic effect. For example, “cell response modifiers” (CRM) 18,as used herein, include agents that control the structure and orfunction of cells in vitro and or in vivo, whereas, “tissue responsemodifiers” (TRM) 20 as used herein, include agents that control thestructure and or function of tissues in vivo and or ex vivo. The CRM 18may include cells genetically engineered and non-genetically engineered:biological cells, synthetic cells, regulatory cells, tissue supportcells, mutant cells, artificial cells, genetically altered cells,chemically altered cells, and/or stem cells. The CRM 18 may controlcellular proliferation; cell injury; cell death; cell metabolism; cellprotein synthesis; cell gene expression; and/or agents that control thestructure and/or function of cells derived from any in vitro or in vivosource.

In one embodiment, the categories or types of cells whose structure andor function is controlled by CRM 18, include cells derived fromembryonic, neonatal, juvenile and or adult cells. In addition, cellsthat may be controlled by CRM 18 include biological cells, eukaryoticcells, prokaryotic cells, vertebrates cells, invertebrates cells, normalcells, cancer cells, mutant cells, engineered cells, artificial cells,stem cells, and/or hybrid cells. In addition, cells controlled by CRM18, include, for example, endothelial cells, fibroblasts, epithelialcells, muscle cells, fat cells, lymphocytes, macrophages, mast cells,polymorphonuclear leukocytes, red blood cells, neurologic cells,osteoblasts, osteoclasts, nerve, fat cells, brain cells, bone cells,tissue derived stem cells, blood derived stem cells, bone derived stemcells.

In one embodiment, the CRM 18, include agents that, for example, controlcell homeostasis by controlling cell functions such as cell activation,cell proliferation, cell metabolism, cell death (including apoptosis),cell differentiation and maturation, cell size, cell composition.

In one embodiment, the TRM includes, for example, agent(s) that controltissue growth; tissue differentiation; tissue injury; innate immuneresponses; acquired immune responses; humoral immune responses; cellmediated immune responses; inflammation; acute inflammation; chronicinflammation; wound healing; regeneration; tissue repair;neovascularization; bone destruction; bone injury, repair and orregeneration; connective tissue destructions; controls connective tissueinjury, repair and regeneration; fat tissue injury, repair and orregeneration; neurologic tissue injury, repair and or regeneration;and/or responses using TRM 20. The TRM 20 may include: cell to cellprotein transporter molecules; antibodies; proteins, modified proteinsand/or recombinant protein; chemicals; drugs; genetic elements;recombinant DNA; RNAs, including siRNA; altered RNAs; geneticallyaltered RNAs; chemically altered RNAs; DNA; altered DNAs; carbohydrates;lipids and fatty acids; radiation energy; magnetic energy; viruses;single or double strained DNA; and/or single or double strained RNA.

The TRM 20 may be used in combination, for example, the TRM 20 mayinclude: TRM that controls tissue injury and a second TRM that controlsinflammation; TRM that controls inflammation and a second TRM thatcontrols fibrosis; TRM that controls inflammation and a second TRM thatcontrols neovascularization; TRM that controls inflammation and a secondTRM that controls tissue regeneration; TRM that controls cell injury anda second TRM that controls inflammation; TRM that controls cell deathand a second TRM that controls inflammation; TRM that controlsinflammation and a second TRM that controls fibrosis; TRM that controlsinflammation and a second TRM that controls neovascularization; TRM thatcontrols fibrosis and a second TRM that controls neovascularization;and/or TRM that controls inflammation and a second TRM that controlstissue regeneration.

The TRM 20 may, for example, in one embodiment include the agents2-(3-benzophenyl)propionic acid,9-alpha-fluoro-16-alpha-methylprednisolone, methyl prednisone,fluoroxyprednisolone, 17-hydroxycorticosterone, cyclosporin,(+)-6-methoxy-.alpha.-methyl-2-naphthalene acetic acid,4-isobutyl-.alpha.-methylphenyl acetic acid, Mitomicyin C,Acetaminophen, Dexamethasone, Diphenyhdramine, Hydrochloride, Cromolyn,3-(1H-Tetrazol-5-yl)-9H-thiol-xanthene-9-one 10,10-dioxide monohydrate,H1 and H2 histamine antagonists (H1 antagonists: mepytramine ortriprolidine) transforming growth factor alpha, anti-transforming growthfactor beta, epidermal growth factor, vascular endothelial growthfactor, anti-transforming growth factor beta antibody, anti-fibroblastantibody, anti-transforming growth factor beta receptor antibody,arginine-glycine-aspartic acid, REDV, or a combination thereof.

Categories of tissues whose normal structure and or function iscontrolled by TRM, include, for example, biological tissues ofvertebrates, invertebrates; normal tissue; injured tissue; regeneratingtissue; repairing tissue; cancer tissue; mutant tissue; engineeredtissue; artificial tissue; stem cell tissues; hybrid tissues;endothelial tissue; fibroblasts; epithelial tissue; muscle tissue; fattissue; lymphocytes; macrophages; mast tissue; polymorphonuclearleukocytes; red blood cells, soft tissue; neurologic tissue;osteoblasts; osteoclasts; nerve; brain tissue; bone tissue; tissuederived stem tissue; blood derived stem tissue; and/or bone derived stemtissue.

Categories of tissues whose structure or function is controlled by TRMex vivo include, for example, tissues originally derived from embryonic,neonatal, juvenile and/or adult tissues. Categories of tissues whosestructure or function is controlled by TRM in vivo and or ex vivoinclude, for example, embryonic tissues, neonatal tissues, juvenile oradult skin. Injured tissues controlled in vivo and or ex vivo by TRM,include, for example, normal embryonic tissues, neonatal tissues,juvenile or adult skin. Tissues controlled in vivo and or ex vivo byTRM, include, for example, include embryonic tissues, neonatal tissues,juvenile or adult soft tissue, hard tissue, e.g. bone), skin, cardiacsystem, pulmonary, hepatic, gastrointestinal tract, biliary tract,urinary tract, genital tract, vision, neurologic or endocrine systems,blood vessels, bones, joints, tendons, nerves, muscles, the head, theneck, or any organ system or combinations thereof.

In one embodiment, factors that are used to control vascular endothelialcell function in vitro (i.e. cell response modifiers 18) also may induceor suppress new blood vessel formation in vivo thus under the rightcircumstances they are also tissue response modifiers 20. For example,these factors may include: Vascular Endothelial Growth Factor (VEGF);Fibroblast Growth Factor (FGF); Interleukin-8 (IL-8); Angiogenin;Angiotropin; Epidermal Growth Factor (EGF); Platelet Derived EndothelialCell Growth Factor; Transforming Growth Factor α (TGF-α); TransformingGrowth Factor β (TGF-β); Nitric Oxide; Thrombospondin; Angiostatin; andEndostatin. In one embodiment, cell response modifiers 18 are used, butbecause they also operate to control inflammation and immune responsesas well as development in vivo they are also examples of cell responsemodifiers that can act in vivo as tissue response modifiers 20. Forexample, cytokines and growth factors included in this operativedefinition include: TH1/TH2 Interleukins (IL-2, IL-4, IL-7, IL-9, IL-10,IL-12, IL-13, IL-15, IL-16, IL-17); the IL-1 family (IL-1-alpha, IL-1Ra,IL-18, IL-1-beta); the TNF family, for example TNF Ligand and TNF/NGFReceptor Families, TNFalpha, Lymphotoxin alpha and beta, Fas Ligand,CD40 Ligand, CD30 Ligand, CD27 Ligand, RANK Ligand Apo2L/TRAIL; the IL-6family, for example, IL-6 Ligand and Receptor Family, IL-6, IL-11,Oncostatin M, CT-1; macrophage activation, such as, IFNalpha, IFN beta,and IFNomega Ligands, IFNgamma, Osteopontin, MIF; TGF beta, BMP Family,PDGF, VEGF, Poxvirus Vascular Endothelial Growth Factor (VEGF) Homologsof Orf Virus, Angiostatin, Activin, Endostatin, Methoxyestradiol,Poxvirus Growth Factors Related to EGF; IL-3, IL-5, Stem Cell Factor,GM-CSF CSF-1, G-CSF, Erythropoietin, Thrombopoietin; MGSA/GRO, ENA-78,IL-8, H. GCP-2, A. CTAP-III, betaTG, and NAP-2, Platelet Factor 4, IP-10MIG, SDF-1, BLR1 Ligand/BCA-1/BLC, 9E3/cCAF; MCP-1, MCP-2, MCP-3, MCP-4,and MCP-5 RANTES, 1-309, MIP-alpha, MIP-beta, Eotaxin, PARC, Eotaxin 2,MIP-gamma/MRP-2, Mu C10, Leukotactin 1, CKbeta8-, B. HCC-1, SLC(6CKine), ELC, H TECK/CCL25, CC Chemokine of Molluscum ContagiosumVirus, Lymphotactin, Fractalkine, Poxvirus Secreted Complement ControlProteins; IL-2 Family Receptors, IL-2 Receptor, IL-4 Receptor, IL-7Receptor, IL-9 Receptor, IL-10 Receptor, IL-12 Receptor, IL-13 Receptor,IL-15 Receptor, IL-16 Receptor (CD4), IL-17 Receptor, ProlactinReceptor; IL-1 Family Receptors, such as, IL-1 Receptor Family, IL-1Receptor Type I, Poxvirus IL-1beta Receptor Homologs, IL-18 Receptor,IL-1 Receptor Type II; TNF Receptors, Poxvirus TNF Receptor Homologs,Lymphotoxin beta Receptor, Fas, CD40, CD30, 4-1BB, RANK,Osteoprotegerin, CD27, HVEM, DR4, DR5, DcR1, DcR2, DcR3, Ox40, GITReceptor; IL-6 Receptor; IL-11 Receptor, OSM Receptor, CT-1 Receptor;IFNgamma Receptor, Poxvirus IFNgamma Receptor Homologs, IFN c betaReceptor, Poxvirus IFN c beta Receptor Homologs, Osteopontin Receptor,TGF beta Receptors, BMP Receptor, Hematopoietic Receptors, for examplethe Hematopoietic Receptor Family of IL-3 Receptor, IL-5 Receptor, SCFReceptor, GM-CSF Receptor, G-CSF Receptor, TPO Receptor; CXC ChemokineReceptors, such as, CXCR1 and CXCR2, CXCR3, CXCR4, CXCR5, R. CC, C, andCX3C; CC Chemokine Receptors, such as, CCR1, CCR2, CCR3, CCR4, CCR5,CCR6, CCR7, CCR8, D6, ECRF3, Poxvirus Membrane-bound G Protein-coupledReceptor Homologs, US28, Kaposi's Sarcoma-associated Herpesvirus GPCR,DARC, CX3CR1, Poxvirus Secreted Chemokine-binding Proteins, CCR9, XCR1;and Miscellaneous non-Cytokine Proinflammatory Factor Receptor, such asC5a Receptor, C3a Receptor, PAF Receptors, fMLP Receptors, Opioid mu,delta, and kappaReceptors for Endorphins, Lipoxin A4 Receptor, ACTHReceptor, BLTR: the Leukotriene B4 Receptor, PACAP and VIP Receptors,Lysophospholipid Growth Factor Receptors.

In one embodiment stem or progenitor cells 14 c are included in the ATS.These stem or progenitor cells may be included in a matrix material 22,which is selected based on the origin of the stem or progenitor cells.For example, expansion of undifferentiated stem cells, in vitro, may beaccomplished with a gelatin matrix material; expansion of nestin+neuralprogenitor cells may be accomplished with laminin, RA, Survival ofembryonic stem cell derived motor neurons with basement membrane, andendothelial cells with collagen IV. If, for example, the stem orprogenitor cells are of a bone marrow origin of the MSC, MAPC, or HSCtype, then fibronectin and or basement membranes may be used. Forexample, expansion in vitro of undifferentiated MAPCs with fibronectin;osteoblasts with fibronectin; endothelial cells with fibronectin; andhepatocyte-like cells: basement membranes. If, for example, the stem orprogenitor cells are of an adult tissue origin of the hepatic oval cell,NSC/NPC, adipose stem cell, or MDSC type, then fibronectin, lamininand/or collagen may be used. For example, expansion of undifferentiatedoval cells with fibronectin; hepatocyte with fibronectin; pancreaticislet with fibronectin; neuron, glial cells with fibronectin, laminin;expansion of MDSCs with collagen, and osteoblast with collagen.

In one embodiment, several growth factors or cytokines may be used as,for example, CRM 18 to promote stem or progenitor cell proliferation anddifferentiation in vitro. For example, if the stem or progenitor cellsare embryonic stem cells, then expansion of undifferentiated ES cellscan be accomplished with LIF; pancreatic endocrine progenitor with bFGF;pancreatic islet with bFGF; expansion of Nestin+neural progenitors withbFGF; RASurvival of ES-derived motor neurons with BDNF, NT-3, CNTF,GDNF; glial progenitor cells with bFGF, PDGF-AA;adipocyte13RAChondrocyte with BMP-2, BMP-4; dendritic cells: GM-CSF,IL-3; and endothelial cells with VEGF. If the stem or progenitor cellsare derived from bone marrow and are of the MSC, MAPC, or HSC types,then, for example, osteoblast may be utilized with BMP-2, bFGF;chondrocyte with TGF-ß3; neuron, glial cells with EGF, BDNF; expansionof undifferentiated MAPCs with EGF, PDGF-BB; chondrocyte with TGF-ß1;endothelial cells with VEGF; hepatocyte-like cells with FGF-4, HGF; andplatelets, red/white blood cells with IL-3, IL-6, G-CSF. If the stem orprogenitor cells are derived from adult tissues and are of the Hepaticoval cell, NSC/NPC, Adipose stem cell or MDSC types, then, for example,expansion of undifferentiated oval cells can be accomplished with SCF,Flt-3 ligand, IL-3, LIF; hepatocyte with HGF, EGF; pancreatic islet withSCF, Flt-3 ligand, IL-3; expansion of NPCs with bFGF, EGF, LIF; neuron,glial cells with bFGF, EGF, PDGF-AA, PDGF-AB, PDGF-BB, NT-4, CNTF;osteoblast with TGF-ß1; expansion of MDSCs with IGF-1, EGF, SCF, FGF2;and osteoblast: BMP-2.

In one embodiment stem or progenitor cells 14 c are promoted utilizingother factors as, for example, TRM 20. For example, if the stem orprogenitor cells are embryonic stem cells, then pancreatic islet cellscan be utilized with nicotinamide; expansion of Nestin+neuralprogenitors can be accomplished with poly-ornithine; neurons withpoly-ornithine, RA; Adipocytes with RA; and osteoblasts with RA,dexamethasone, ascorbate, ß-glycerol phosphate. If the stem orprogenitor cells are derived from bone marrow and are of the MSC, MAPC,or HSC types, then, for example, osteoblasts with dexamethasone,ascorbate, ß-glycerol phosphate; chondrocytes with dexamethasone;neuron, glial cells with RA; adipocytes with dexamethasone, insulin,indomethacin, 1-methyl-3-isobutylxanthine; expansion of undifferentiatedMAPCs with 2% FBS; osteoblasts with dexamethasone, ascorbate, ß-glycerolphosphate; platelets, red/white blood cells with erythropoietin,thrombopoietin. If the stem or progenitor cells are derived from adulttissues and are of the Hepatic oval cell, NSC/NPC, Adipose stem cell orMDSC types, then, for example, pancreatic islet cells can be utilizedwith nicotinamide; osteoblasts with Dexamethasone, ascorbate, ß-glycerolphosphate; chondrocytes with insulin, ascorbate; and adipocytes withdexamethasone, insulin, indomethacin, 1-methyl-3-isobutylxanthine.

FIG. 24 provides a list of angiogenic factors. VEGF-A induces both bloodvessels and lymphatic vessels. VEGF-C and VEGF-D induce a predominanceof lymphatic vessel and some blood vessels.

Method of Applying Coatings

In the embodiments shown in FIG. 3, as well as embodiments describedbelow and shown in other figures, multiple layers of a single type ofcoating optionally can be applied, or a single coating can be used. Theoverall method of coating is designated as 100. While the method isdescribed in connection with sensors, the same method applies tocannulas and collars (that are not themselves made of ECM), and also tosurgical mesh.

In other embodiments, multiple layers of different ECMs can be appliedto a device. The various layers can have different cells and/or factorsincorporated therein.

In the embodiment shown in FIG. 3, multiple layers of a single type ofcoating are applied. The overall method of coating is designated as 100.Referring to FIG. 3, a device is obtained at 102 and an extracellularmatrix material to be used as a coating material is obtained at 104. Thecoating is configured in liquid or gel form based on the temperature ofthe coating material (MATRIGEL® matrix will start to form a gel at orabove 10 Deg. C and will gel rapidly at 22-35 Deg. C). The device ispartially or fully coated with the coating material at 106 by dipping,spraying, brushing or another suitable technique. The coating is driedat 108. Drying can take place at room temperature, at elevatedtemperature, or at a temperature below room temperature including 4 deg.C. The coatings can be dried passively at room temperature or abovethrough the uses of fans/blowers or heating devices at room temperatureor above (gel) or 4 deg. C. (liquid).

Drying the liquid or gelatinous basement membrane at differenttemperatures likely would change the structures and orientation of theproteins and factors in the basement membrane (for example cross linkingoccurs as a result of drying). For a coating material such assolubilized basement membrane, which typically is a liquid at 4 degreescentigrade and a gel above 10 degrees centigrade.

Optionally, additional coatings can be added before the sensor is usedor packaged. As shown in FIG. 3, after drying at 108, a second coatingof the same material is applied at 110 and the coating is dried at 112.Optionally, a third layer of the extracellular matrix material isapplied at 114 and then dried at 116. Additional coating and dryingstages optionally can take place at 118. In some cases, the device ispackaged at 120 for later use. When the packaged device is to be used,it is rehydrated before or after implantation, or both, at 122. In othercases, the device is used without being stored or packaged. When used,the device can be rehydrated before or after implantation, or both, at124. This is done in order to eliminate salts, which have accumulated inthe dry coating (toxic to tissue) and also since a sensor with a drymembrane is easier to implant. The wet MATRIGEL® is easily sheared offthe sensor surface during implantation. Having it dry is good forstorage and shipping since refrigeration is not necessarily needed.Hydrating solution can be aqueous or non-aqueous solutions and cancontain additives, such as proteins, drugs, antibodies. In embodiments,the device is rehydrated, dried and implanted at 126. In the embodimentshown in FIG. 4, multiple layers of various coatings are applied. Theoverall method of coating is designated as 200. Referring to FIG. 4, adevice is obtained at 202 and a material (which may or may not be anextracellular matrix) to be used as a coating material is obtained at204. The coating is configured in liquid or gel form. The device ispartially or fully coated with the coating material at 206 by dipping,spraying, or another suitable technique. The coating is dried at 208.Drying can take place at room temperature, at elevated temperature, orat a temperature below room temperature. For a coating material such assolubilized basement membrane, it is generally known that the MATRIGEL®is a liquid at 2-10 Deg. C and a gel at 15-30 Deg. C. Optionally,additional coatings can be added before the sensor is used or packaged.As shown in FIG. 4, after drying at 208, a second coating of a differentmaterial is applied at 210 and the coating is dried at 212. Optionally,a third layer of extracellular matrix material is applied at 214 andthen dried at 216. Additional coating and drying stages optionally cantake place at 218. Optionally, the device is packaged at 218 for lateruse at 220. When the device is to be used, it is rehydrated before orafter implantation, or both, at 222 or 224. At least two of the coatingsare made of extracellular matrix. In embodiments, all of the layers aremade of extracellular matrix.

FIG. 5 shows photographs of the coating process. A sensor is dipped inbasement membrane, such as MATRIGEL®, that is in the form of a liquid.The basement membrane is then dried. A second coat of the same or adifferent extracellular matrix is then applied and dried. Multiplecoatings can be applied and dried. When the sensor is ready for use, themultilayer coating is hydrated to rinse away salts, retried, andimplanted in biological tissue.

In embodiments, various VEGFs (VEGF-A, VEGF-B, VEGF-C, and/or VEGF-D)individually or in combination are bound to fibronectin (FN). TheVEGF-fibronectin combination in turn can be added to ECM preparationssuch as basement membranes to make a complex that is coated on animplantable device and implanted in a dry or wet form in biologicaltissue. The ECM-fibronectin-VEGF combination will induce formation ofaddition vascular networks, thereby extending the useful lifespan of thedevice.

Methods Employed for Gene Transfer

In embodiments, there are a wide variety of methods employed for genetransfer in cells and tissue. Three of the major approaches usedinclude: 1) plasmid based gene transfer, 2) retrovector based genetransfer and 3) adenovector based gene transfer. Plasmid based genetransfer utilizes “naked” DNA to directly transfer genetic informationinto cells in vitro and or in vivo. Plasmid based gene transfer has theadvantage that it is simple, but it is extremely inefficient,particularly in vivo. Retrovector based gene transfer utilizesretroviral vectors to “carry” the selected genetic information into thecells via specific virus receptors on the surface of target cells.Retrovectors have the advantage in that they are extremely stable, butthey require a selection procedure, which identifies cells in which thegenes have successfully been transferred. Adenovectors, likeretrovectors utilizes adenoviral vectors to “carry” the selected geneticinformation into the cells via specific virus receptors on the surfaceof target cells. Adenovectors have the advantage of being very efficientin gene transfer also the gene expression may be transient. Generallyfor gene therapy, adenovectors have been the system of choice.Adenovirus binds to a surface receptor known as CAR, and CARs have beenidentified on human (hCAR) and murine cells. Unfortunately not all cellshave high enough levels of CAR to allow infection with adenovectors,thus limiting the spectrum of target cells in which gene transfer can beachieved. For example, generally fibroblasts have limited levels of CARand thus are not used as target cells for adenovector based genetransfer. For the ATS, a protocol for genes transferred into targetcells that are CAR deficient, thus allowing the use of adenovector inthese cells.

Many of the materials listed above are described in U.S. patentapplication Ser. No. 10/578,171, Klueh et al., filed May 4, 2006(published as US Patent Publication Number 2007/0077265 on Apr. 5,2007), the contents of which are incorporated by reference herein intheir entirety.

Neovascularization

CGM technology allows the patient to monitor their glucose level inreal-time and as such, alerts the user when glucose levels are fallingtoo low or rising too high. This knowledge can help the user to preventpotential harmful hyperglycemic or hypoglycemic events. Both of theseevents are damaging to the body's vasculature system and ultimatelyresponsible for diabetes complications including death. Crucial to goodCGM performance is an accurate glucose sensor.

Gene therapy studies described herein demonstrate that 1) VEGF-A basedlocal gene therapy increases vascular networks (blood vessels andlymphatic vessels) at sites of glucose sensor implantation; and 2) thislocal increase of vascular networks enhances and extends glucose sensorfunction in vivo. This data shows that increasing vascular networks atsites of glucose sensor implantation enhances and extends continuousglucose monitoring (CGM) in vivo.

The formation of new BV is essential to embryonic development, woundhealing and tumor growth in vivo. Central to all these various forms ofnew vessel formation is the local expression of angiogenic factors (AFs)such as VEGF, HGF, PDGF, IL-8, etc. (also see FIG. 24). These AFs play akey role in initiating new vessel formation in vivo, i.e. angiogenesis.During neovascularization, new BVs emerge and develop from preexistingvessels through various processes, which include vascular endothelialcell (VEC) proliferation and migration. This initial sequence of eventsresults in tissue invasion by developing capillary sprouts. Uponformation of capillary sprouts, endothelial cells migrate toward theangiogenic stimulus into regeneration or developing tissue. Ultimately,tube to-tube connections are made by the capillary sprouts in order toobtain continuous blood flow.

Generally, BVs play a vital role in the delivery of nutrition (glucose)and oxygen to tissues, as well as the removal of CO₂ from the tissues.Additionally, these same networks of BVs are also critical to thedelivery of inflammatory and immune cells to sites of injury, infectionand wound healing. However, the various roles of LVs, as well as theirstructure and development, L-Angio, are generally not appreciated in theglucose sensor community. LVs are blind vessels, which arise withinvirtually all tissues. Outflow of the LVs as toward the lymph nodes ismaintained by a series of leaflet valves, which allow uni-direction flowwithin the LVs. In normal tissues the lymphatics represent the majoroutflow of fluids and cells within the interstitial compartment, and assuch have significant impact on interstitial flow and glucose levels.The fluids and cells that flow thru the LVs accumulate within the lymphnode, and eventually drainage of the lymph node occurs back into theblood stream for eventual recirculation (e.g. lymphocytes andmacrophages) or removal thru the kidneys and bowel. During tissuetrauma, inflammation and wound healing, lymphatics play a critical rolein draining excessive fluids (edema), tissue debris and inflammatorycells from the site of injury and thereby decreasing inflammation. Thisdrainage is critical to minimizing additional tissue damage by removingall factors and cells from the trauma site and thereby promoting tissuerepair and regeneration. In fact, a growing body of literature hasdemonstrated that 1) blocking lymphangiogensis enhances inflammation andtissue destruction and 2) enhancing LV number and function diminishesinflammation in a number of disease states.

The VEGF-A induced lymphatic vessels can be important in tissue drainageto reduce inflammation and tissue injury, including fluids (edema) andinflammatory cells associated with angiogenesis. The major control ofboth hemangiogenesis (H-Angio) and L-Angio appears to be through arelated group of agonists and receptors known as the VascularEndothelial Growth Factor (VEGF) family. The VEGF family is primarilycomposed of 4 agonists (VEGF-A, VEGF-B, VEGF-C, VEGF-D) with overlappingfunctions via their receptors. The agonists exert their angiogenicaction on blood vessels (VEGF-A) and lymphatic endothelial cells (ECs)(VEGF-C and VEGF-D) thru 3 receptors present on the surfaces of thesecells. Because of the central role of the VEGF family in human diseasessuch as cancer and inflammation, a number of antagonists of the variousmembers of the VEGF family have been developed.

The VEGF family also plays a critical role in controlling wound healing,i.e. repair and regeneration. This central role of the VEGF family inwound healing is the result of the VEGF family's ability to control theformation of vascular networks at sites of tissue injury andinflammation. The ability of the VEGF family to control the formation ofblood vessels and lymphatic vessels controls not only the influx offluids, nutrients (glucose), oxygen and cells into the injured site topromote healing, but it also allows the removal of fluids(edema/swelling), tissue debris, and toxic factors as well as theremoval of inflammatory cells all of which reduce inflammation andtissue injury and enhance and extend glucose sensor function andcontinuous glucose monitoring (CGM).

Frequently, unreliable glucose sensor function in vivo is the result ofacute and chronic tissue reactions at the sensor implantation site (i.e.inflammation, fibrosis and vessel regression). These tissue reactionslimit sensor function by 1) damaging (inflammation) and regressing(fibrosis) vascular networks (blood and lymphatic) that controlreal-time movement of fluids (Glucose) and cells (leukocytes) withintissue and 2) by inducing sensor “biofouling”, including creation ofleukocyte based “metabolic barriers” surrounding the sensors.Specifically, the loss of blood vessels results in loss of real-timeblood glucose levels in the interstitial spaces. The loss of lymphaticnetworks at implantation sites prevents efficient drainage of tissuedebris and inflammatory cells from the implantation site. The failure toproperly drain inflammatory cells from implantation sites increases the“inflammatory load” at the implantation sites, thus increasingbiofouling and loss of sensor accuracy. The data provided below showsthat enhancing both blood vessel (BVs) and lymphatic vessel (LVs)networks at sensor implantation improves the accuracy and extends thefunctional lifespan of a sensor in continuous glucose monitoring.

In addition to the VEGF families of agonists and receptors, additionallymphangiogenic agonists/receptors have also been identified (FIG. 24).As is the case with the VEGF family the agonists can be expressed by avariety of cells if the corresponding receptor is present on lymphaticendothelial cells. The major LymphAngiogenic factors/receptors includeInsulin-like Growth Factor (IGF)/IGF-1R; Platelet Derived GrowthFactor-BB (PDGF-BB)/PDGFa/B; Angiopoietin-1 (Ang-1)/Tie-2 and HGF/HG-R 4(FIG. 24).

System Comprising Kit

In embodiments, a system is provided comprising a kit that includes atleast one extracellular matrix, a device to apply the ECM to animplantable device such as a cannula, or catheter, a protocol for usingthe kit to coat the implant with at least one layer of ECM as well as aspecific drying and hydrating method described.

In another embodiment, a system is provided comprising a kit thatincludes at least one extracellular matrix, a device to apply the ECM toan implantable medical device, with the ECM being applied as a collar orsleeve, and a protocol for using the kit to coat the implant with atleast one layer of ECM as well as a specific drying and hydrating methoddescribed.

Embodiments Using Crosslinked Basement Membrane

FIG. 42 shows a coated implant 210, which includes an implantable device212 which is surrounded by a coating layer 214 of crosslinked basementmembrane. FIG. 43 shows a coated implant 220, which includes animplantable device 222, which is surrounded by an inner coating layer224 of crosslinked basement membrane and an outer coating 226 ofbasement membrane that is not crosslinked. Alternatively, both the innerand outer coating layers may be crosslinked, either in a singlecrosslinking step or in separate crosslinking steps. In anotherembodiment, the inner layer is not crosslinked and the outer layer iscrosslinked. Furthermore, additional crosslinked or non-crosslinkedlayers can be added over layer 226. In embodiments, the basementmembrane layers can be added in liquid or gel form. In embodiments,pre-dried, crosslinked or non-crosslinked basement membrane layers canbe applied on or beneath liquid and/or gel layers, or directly on theimplantable device as the inner layer. In embodiments, the pre-driedlayers are in the form of sheets.

FIG. 44 shows a coated implant 230, which include an implantable device232, which is surrounded by an inner coating layer 234 of a drug releasesystem, and an outer coating layer 236 of crosslinked basement membrane.In alternative embodiments, the intermediate layer is crosslinked andthe outer layer with their crosslinked or not crosslinked. FIG. 45 showsa coated implant 240 which includes an implantable device, 242, an innercoating layer 244 of a drug release system, an intermediate coatinglayer 246 of cross-linked basement membrane, and an outer coating layer238 of basement membrane that is not crosslinked. The order of thelayers can be varied. FIG. 46 shows a coated implant 250 with animplantable device 252 having a coating comprising a crosslinkedbasement membrane that contains natural or synthetic fiber and ormatrices. Such materials can be added, for example, to impart additionalstrength to the layer. Non-limiting examples of natural fibrousadditives include fibrin; collagens (Fibrillar (Type I, II, III, V, XI);Facit (Type IX, XII, XIV); Short chain (Type VIII, X); Basement membrane(Type IV); Other (Type VI, VII, XIII); fibronectins; laminins; elastins;and Proteoglycans: (Chondroitin sulfate, Heparan sulfate, Keratansulfate, Hyaluronic acid). Non-limiting examples of synthetic fibrousinclude Polyurethane; Polysulfone; Calcium phosphate; Hyaluronic acid;Polypropylene; Bioactive glass; Extracellular matrix; Polyvinyl alcohol;Polyglycolide; Polylactide; Poly(propylene fumarate); Polycyanoacrylate;Poly(ε-caprolactone); Polydioxanone; Polyhydroxyalkanoates; Poly(orthoester); Poly(ether ester); Poly(ethylene oxide); Polybutyleneterephthalate; Hydroxyapatite; Tricalcium phosphate; Poly(ethyleneglycol); Poly(ester urethane); Poly(acrylic acid); Lysine diisocyanate;Biphasic calcium phosphate; Polyacrylamide; Polymethylmethacrylate;Poly(L-lactic acid); Poly(l-lactide-co-glycolide); Poly(trimethylenecarbonate); Polydimethylsiloxane; Polytetrafluoroethylene;Poly(ethylene-co-vinylacetate); Poly(glycolide-co-ε-caprolactone);Poly(l-lactide-co-caprolactone); Poly(DL-lactide); Poly-L/D-lactide;Poly(lactic acid-glycolic acid); Poly(3-hydroxybutyrate)3-hydroxyvalerate; Poly(caprolactone-co-trimethylene carbonate);Poly(N-isopropylacrylamide); Poly(dimethylam inoethylmethacrylate)hydrochloride; Poly(D, L-lactide-co-caprolactone);Poly(l-lactide-co-ε-caprolactone); Tricalcium phosphate.

In further embodiments, one or more layers contain factors, drugs,agents, proteases and protease inhibitor, tissue and cell responsemodifiers virus, genetic material, and cells as described above.

In general, the material of the embodiments described herein may bealternately formulated to comprise, consist of, or consist essentiallyof, any appropriate components herein disclosed. The material of thedisclosed embodiments may additionally, or alternatively, be formulatedso as to be devoid, or substantially free, of any components, materials,ingredients, factors, cellular constituents, cytokines, growth factors,tissue types, genetic elements, adjuvants or species used in the priorart compositions or that are otherwise not necessary to the achievementof the function and/or objectives of the described embodiments.

EXAMPLES

Gene therapy studies described below demonstrate that 1) VEGF-A basedlocal gene therapy increases vascular networks (blood vessels andlymphatic vessels) at sites of glucose sensor implantation; and 2) thislocal increase of vascular networks enhances and extends glucose sensorfunction in vivo (FIG. 7, 8, 9, 10, 11, 12). This data shows thatincreasing vascular networks at sites of glucose sensor implantationenhances continuous glucose monitoring (CGM) performance in vivo.

Example 1A—Impact of Local Vascular Endothelial Cell Growth Factor GeneTherapy on Continuous Glucose Monitoring

To induce sustained vascular networks at sites of sensor implantation,the potential of local VEGF gene therapy to extend sensor function andCGM in a murine model was investigated. Specifically, the impact wasdetermined of direct injection of adenovirus vectors containing mouseVEGF gene (AdvVEGF) or AdvLacZ (control virus) at the sites of glucosesensor implantation in vivo (FIG. 6). Injections of viruses or solutionswere done at the sensor tip post sensor implantation (see FIG. 6B,arrow). The injection procedure was as follows:

Detailed Description of Mouse Surgery:

The mice were anesthetized while being monitored for withdrawal reflex,heart rate, respiratory rate, color, and vital signs to ensureappropriate anesthesia before surgical procedures were performed. Priorto the sensor implantation, the back of the mouse was clipped, shaved,and prepared with Betadine solutions. Prior to sensor implantation, 100to 200 ml of injectable sterile, pyrogen free, 0.9% NaCl was injectedsubcutaneously (s. c.) in the back area of the anesthetized mouse toprovide an “implantation pocket”. The implantation pocket is used tominimize tissue and sensor damage during sensor implantation. A smallopening was made in the “implantation pocket” using a 23 to 25-gaugeneedle and the sensor was then implanted in the subcutaneous pocket withthe sensor leads exposed. The size of the sensor implanted was about 0.5mm in diameter×1 cm long. A small polyester mesh was placed on top ofthe exposed sensor leads. Sensor leads and nylon mesh were secured tothe shaved mouse skin by applying a coating of NewSkin (Liquid Bandage).Mice were kept under anesthesia until New Skin Liquid Bandage was dried.Once sensors are implanted, mice were housed individually as aprecaution to prevent dislodging of the sensor. Periodic blood glucoselevels were obtained in the sensor implanted mice. The adenovirusvectors containing VEGF gene (or a control) were injected (30 ul ofsaline containing virus or saline alone) at site of sensor implantationat various times post sensor implantation (FIG. 6). 1 dosage of virus isinjected for up to 3 different time intervals (e.g. days 5, 6 and 7 postsensor placement).

Additional controls of 1) saline injections and 2) no injections werealso done. For each treatment (injection) sensors were implanted in themice, and on 3 consecutive days (days 6, 7 & 8,) 30 uls of saline,AdvLacZ or AdvVEGF were injected at the implanted sensor tip, i.e. thesensing element of the sensor (see FIG. 6B). After the initial 3injections were completed there were no further treatments. Both pre andpost injection, the mice were allowed to roam freely. It should be notedthat CGM was done for 28 days with 21 days post-adenovirustreatment/injection i.e. (days 7-28) to minimize any impact of acquiredimmunity against adenovirus infected tissue cells 33, 34. CGM output innAs (FIG. 7A-P) was recorded and actual blood glucose levels weredetermined using the Abbott Freestyle external monitor (diamonds in FIG.7A-P). As can be seen in FIG. 7A-D sensors implanted in mice withtreatments of no-injection, saline injection (FIG. 7E-H), and Adv-LacZ(viral vector control) (FIG. 7I-L) injection showed periods where themouse blood glucose (diamonds) did not correspond to sensor output(continuous line). On the other hand, sensors implanted in mice withAdv-VEGF treatment did not experience these sensor functionality losses(Figure M-P).

Impact of VEGF Gene Therapy on Sensor Function

FIG. 7 shows the results of continuous glucose monitoring (CGM) insaline, Adv-LacZ, and Adv-VEGFa injected C57BL/6 mice for up to 28 dayspost sensor implantation (DPI). FIG. 7A-7D shows a control with noinjection. FIG. 7E-7H are representative of CGM in saline (control),FIGS. 7I-7L are representative of Adv-LacZ, and FIGS. 7M-7P arerepresentative of Adv-VEGFa injected C57BL/6 mice for up to 28 days postsensor implantation. Sensor output is expressed as CGS output (nA) andis represented by the lines. Diamonds represent blood glucose levels,and triangles represent injections. For this study a total of 80 micewere evaluated.

Example 1B— Mean Absolute Relative Difference (MARD) Analysis

To assess the impact of local VEGF gene therapy, the resulting CGM datawere analyzed using standard Mean MARD analysis. A difference wasobserved between the four treatment groups, which was statisticallysignificant, as per the Kruskal-Wallis test (p=0.003). The data is shownin FIG. 8. Cumulative average mean MARD from weeks 1 to 4 by treatmentgroup: p-values represent the significance of the difference among thefour treatment groups in average mean MARD value for each of individualweeks, by the non-parametric Kruskal-Wallis test.

FIG. 8 demonstrates the difference and trends in the MARD values betweenthe treatment groups over the course of the 28-day experiment.Adv-VEGF-A treated mice had lower MARD values than all the other controlgroups, demonstrating its effectiveness in improving glucose sensorfunction. In addition, the difference between the Adv-VEGF-A MARD valuesand the other treatment groups grew over the four weeks. In concert withthe timing of the injections around the end of the first week, it wasobserved that the statistical difference between the groups, asevaluated by Kruskal-Wallis tests, was not significant during the firstweek (p=0.205), but becomes statistically significant in weeks 2, 3, and4 (p=0.011, 0.002, and 0.008, respectively).

FIG. 10 shows Average Mean Absolute Relative Difference (MARD) valuesfor all four weeks of mice treated with adenoviral vectors bearingVEGF-A or LacZ (Adv-VEGF-A or Adv-LacZ), and their saline or noinjection controls. FIG. 10 demonstrates the statistical comparisonsbetween the total mean MARDs for mice within each treatment group. Asshown in FIG. 10, it was observed that the Adv-VEGF-A treated mice had atotal (for the entire 4 week testing period) mean MARD of 17.44+1-5.72%,whereas the Saline and No Injection C57BL/6 control mice hadintermediate MARDs of 24.91+/−15.74% and 23.50+/−9.83% respectively, andAdv-LacZ had the worst mean MARD of 31.49+/−14.50%. The Adv-VEGF-Atreated mice had significantly (p<0.05) lower total mean MARD than everyother treatment group, as measured by student t-tests. In addition, theAdv-VEGF-A mean MARD data was normally distributed, and had a smallerstandard deviation than every other group. The sample sizes arerelatively large for such investigations with approximately 15 or moremice in each group.

Example 1C—Blood Vessel Density and Regression Analysis

The measured and calculated density of blood vessels among fourtreatment groups showed a statistically significant increase in thepercent area of tissue surrounding the implanted sensor which wereidentifiable blood vessels, as per immunohistology. The mean percentarea, which was blood vessel, for the Adv-VEGFa treated group of micewas 2.15+/−1.55%, whereas the Adv-LacZ, saline, and no treatment groupshad mean percent blood vessel areas of 0.77+/−0.23%, 0.76+/−0.48%, and1.03+/−0.41%, respectively. The statistical significance of thedifference among the four treatment groups, measured by the ANOVAstatistical test, was a p-value of 0.003. In two tailed student t-testsdirectly comparing the Adv-VEGFa group to the other three treatmentgroups specifically, also showed that the Adv-VEGFa mean percent areawas statistically greater than the Adv-LacZ, saline, and no treatmentgroups, with p-values of 0.02, 0.02, and 0.05 respectively. FIG. 9demonstrates the relative distributions of blood vessel density, througha boxplot of the percent blood vessel area of the respective treatmentgroups. To determine if there was a significant statistical relationshipbetween the observed increase in blood vessel density and improvedsensor function, we conducted a linear regression analysis between bloodvessel density and MARD values. As seen in FIGS. 9, 10, 11 and 12, forthose mice among all treatment groups that survived the entire four weektime course of the experiment and whose blood vessel density around thesensor was measured, a functional improvement of 9.12+/−2.77% decreasein MARD for every 1% increase in blood vessel area was observed. Thisratio was statistically significant with a p-value of 0.005 and had acorrelation R² value of 0.40. In addition, a trend in the significanceof the positive relationship between increased percent area as bloodvessel and improved sensor function can be seen in FIG. 12.

FIG. 12 provides a simple linear regression analysis that was conductedon matching histological samples from all treatment groups, whoselymphatic and blood vessels were quantified in counts per squaremillimeter of mouse back tissue, proximal to the glucose sensorimplantation site. The ratio of lymphatic to blood vessels suggests thatlymphatic and blood vessels growth, formation, and maintenance track ina 1 to 1 ratio. The significance is expressed as p-values withstatistical significance achieved at p<0.05. R² represents thecorrelation between the blood and lymphatic vessel variables, as countsper square millimeter.

The significance of the linear regression models and their coefficientsgrows over the four-week time course of the experiment, with thoseexperiments in the fourth week having the greatest significance. Thistrend parallels the very similar increasing significance of the betterand improving MARD values of the Adv-VEGFa injected mice as compared tothe other treatment groups, over the same four week time course, as seenin FIG. 8. Assuming that Adv-VEGFa injections are efficacious, these twotrends match the results one would expect from the timing of theinjections, which occurred around the end of the first week, i.e. days6, 7, and 8. As seen in FIG. 12, we observe that the statisticalsignificance of the linear regression models and their coefficients, isnot significant during the first and second weeks (p=0.442 and 0.111,respectively), but become statistically significant in weeks 3 and 4(p=0.018 and 0.005, respectively), and consistently grows throughout thefour-week experimental time course.

Example 1D—Analysis of the Impact of Adv-VEGF on Hemangiogenesis atSensor Implantation Sites

To evaluate the impact of Adv-VEGFa and control treatments at sensorimplantation sites, tissue samples were obtained from the implantationsites of the various treatment/injection groups and fixed in Zn buffer.The resulting samples were processed for immunohistochemistry (IHC) forvessel detection and quantitation. Mouse blood vessels were detectedusing anti-mouse CD31²⁷. Non-immune IgG was used as a specificitycontrol for both antibodies. The resulting IHC slides were digitizedusing an Aperio Digital Microscope. The resulting digital images wereanalyzed for hemangiogenesis (H-Angio) using ImageJ (NIH). FIG. 9, BloodVessel Analysis, is a boxplot of blood vessel density as measured bypercent area and treatment group. P-values at the top represent studentt-test p-values for the significance of the difference between thepaired comparisons with Adv-VEGF blood vessel density indicated by thelines.

The resulting data was statistically evaluated using student t-test.Adv-VEGFa induced a 1.9, 2.5, and 2.4 fold increase in mean blood vesselpercent area H-Angio at sensor implantation sites when compared tonon-injected (p=0.025), saline injected (p=0.019) or Adv-LacZ (p=0.004),respectively. These studies clearly demonstrate that Adv-VEGFa increasesH-Angio at sensor implantation sites when compared to non-injected andvarious control treated sensor implantation sites. Equally important isthe fact that sensor performance was also enhanced by Adv-VEGFa whencompared to all controls (see total mean MARD, FIG. 10). These studiesestablish “proof of principle” that increasing H-Angio with Adv-VEGFasignificantly increases sensor function and CGM.

Example 1E—Analysis of the Impact of Adv-VEGF-A on Lymphangiogenesis atSensor Implantation Sites

To evaluate the impact of Adv-VEGF-A and control treatments at sensorimplantation sites, tissue samples were obtained from the implantationsites of the various treatment/injection groups and fixed in Zn buffer.The resulting samples were processed for immunohistochemistry (IHC) forvessel detection and quantitation. Mouse lymph vessels were detectedusing anti-mouse podoplanin(8), while mouse blood vessels wereidentified using anti-CD31 immunohistochemistry. Non-immune IgG was usedas a specificity control for both antibodies. The resulting IHC slideswere digitized using an Aperio Digital Microscope. The resulting digitalimages were analyzed for lymphangiogenesis (L-Angio) using ImageJ (NIH).The mean percent area as lymph vessel, for the Adv-VEGF-A treated groupof mice was 2.12+/−0.81%, whereas the Adv-LacZ, saline, and no treatmentgroups had mean percent lymph vessel areas of 0.67+/−0.46%,0.48+/−0.18%, and 0.91+/−0.66%, respectively. The statisticalsignificance of the difference among the four treatment groups, measuredby the ANOVA statistical test, was a p-value of 2.03×10⁻⁶. FIG. 11demonstrates the relative distributions of lymph vessel density, througha boxplot of the percent lymph vessel area of the respective treatmentgroups. The resulting data was statistically evaluated using studentt-test. Adv-VEGF-A induced a 2.3, 4.5, and 3.2 fold increase in meanlymph vessel percent area L-Angio at sensor implantation sites whencompared to non-injected (p=0.001), saline injected (p=0.0001) orAdv-LacZ (p=0.0002), respectively. These studies clearly demonstratethat Adv-VEGF-A increases L-Angio at sensor implantation sites whencompared to non-injected and various control treated sensor implantationsites. Equally important is the fact that sensor performance was alsoenhanced by Adv-VEGF-A when compared to all controls (see total meanMARD, FIG. 10). These studies establish “proof of principle” thatincreasing L-Angio with Adv-VEGF-A significantly increases sensorfunction and CGM.

Example 1F—Blood Vs Lymph Graph

Lymphatic and blood vessels from histological samples of all treatmentgroups were quantified in counts per square millimeter of mouse backtissue, proximal to the glucose sensor implantation site, as perimmunohistology following staining of selected samples against CD31 andpodoplanin antigens, to identify blood and lymph vessels respectively.In FIG. 12, a graph of the relationship between blood and lymphaticvessel counts for each individual sample is illustrated, with a lineartrend line. In addition, simple linear regression analysis was conductedon these counts per square millimeter of blood and lymphatic vessels inmouse back tissue. The ratio of lymphatic to blood vessels (1.06+/−0.25)suggests that lymphatic and blood vessel growth, formation, andmaintenance track in a 1 to 1 correspondence, which is consistent withother observations, particular in cornea experimental models (ref).Particularly in response to VEGF-A, the vessel growth of both blood andlymph vessels are biologically coordinated. As shown in FIG. 13B, thelinear regression model of this blood and lymph coordination from ourhistological observations was very significant (p=0.0001), particularlysince the sample size for this model was relatively large (n=39). R²represents the statistical correlation between the blood and lymphaticvessel variables, as counts per square millimeter, and was 0.33.

Example 1G—Lymph Vessel Density and Regression Analysis

To determine if there was a significant statistical relationship betweenthe observed increase in lymph vessel density and improved sensorfunction, we conducted a linear regression analysis between lymph vesseldensity and MARD values.

FIG. 13C provides a simple linear regression analysis to determine thecontribution of lymph vessel density to glucose sensor function.Reduction in average Mean Absolute Relative Difference (MARD) valuesrepresents an improvement in glucose sensor function. Quantifiedincreases in lymphatic vessels, as measured in percent area as lymphaticvessel, are determined to decrease MARD values by the ratios in thetable above, and therefore improve glucose sensor function. The resultsare tabulated for all data combined (total) and cumulative one, two,three, and four weeks only, i.e. all those mice that survive into thefirst, second, third, and fourth weeks respectively. The significance isexpressed as p-values with statistical significance achieved at p<0.05.R² represents the correlation between MARD and percent area as lymphaticvessel variables.

As seen in FIG. 13C, for those mice among all treatment groups thatsurvived the entire four week time course of the experiment and whoselymph vessel density around the sensor was measured, a functionalimprovement of −4.29+/−1.70% decrease in MARD for every 1% increase inlymph vessel area was observed. This ratio was statistically significantwith a p-value of 0.024 and had a correlation R² value of 0.30. Inaddition, a trend in the significance of the positive relationshipbetween increased percent area as lymph vessel and improved sensorfunction can be seen in FIG. 13C. The significance of the linearregression models and their coefficients grows over the four-week timecourse of the experiment, with those experiments in the fourth weekhaving the greatest significance. This trend parallels the very similarincreasing significance of the better and improving MARD values of theAdv-VEGF-A injected mice as compared to the other treatment groups, overthe same four week time course, as seen in FIG. 8. Assuming thatAdv-VEGF-A injections are efficacious, these two trends match theresults one would expect from the timing of the injections, whichoccurred around the end of the first week, i.e. days 6, 7, and 8. Asseen in FIG. 13C, we observe that the statistical significance of thelinear regression models and their coefficients, are not significantduring the first, second, or third weeks (p=0.69, 0.226, and 0.080respectively), but become statistically significant only in week 4(p=0.024), but consistently grows throughout the four week experimentaltime course. The linear regression model was also statistically over theentire 4 week time course, (p=0.046).

By comparison, the mean percent area as blood vessel, for the Adv-VEGFtreated group of mice was 2.15+/−1.55%, whereas the Adv-LacZ, saline,and no treatment groups had mean percent blood vessel areas of0.77+/−0.23%, 0.76+/−0.48%, and 1.03+/−0.41%, respectively. Thestatistical significance of the difference among the four treatmentgroups, measured by the ANOVA statistical test, was a p-value of 0.003.In two tailed student t-tests directly comparing the Adv-VEGF group tothe other three treatment groups specifically, also showed that theAdv-VEGF mean percent area was statistically greater than the Adv-LacZ,saline, and no treatment groups, with p-values of 0.02, 0.04, and 0.05respectively (FIG. 9). FIG. 11 demonstrates the relative distributionsof blood vessel density, through a boxplot of the percent blood vesselarea of the respective treatment groups. To determine if there was asignificant statistical relationship between the observed increase inblood vessel density and improved sensor function, we conducted a linearregression analysis between blood vessel density and MARD values.

FIG. 13A provides a simple linear regression analysis was conducted todetermine the contribution of blood vessel density to glucose sensorfunction. Reduction in average Mean Absolute Relative Difference (MARD)values represents an improvement in glucose sensor function. Quantifiedincreases in blood vessels, as measured in percent area as blood vessel,are determined to decrease MARD values by the ratios in the table above,and therefore improve glucose sensor function. The results are tabulatedfor all data combined (total) and cumulative one, two, three, and fourweeks only, i.e. all those mice that survive into the first, second,third, and fourth weeks respectively. The significance is expressed asp-values with statistical significance achieved at p<0.05. R² representsthe correlation between MARD and percent area as blood vessel variables.

As seen in FIG. 13A, for those mice among all treatment groups thatsurvived the entire four week time course of the experiment and whoseblood vessel density around the sensor was measured, a functionalimprovement of 9.12+/−2.77% decrease in MARD for every 1% increase inblood vessel area was observed. This ratio was statistically significantwith a p-value of 0.005 and had a correlation R² value of 0.40. Inaddition, a trend in the significance of the positive relationshipbetween increased percent area as blood vessel and improved sensorfunction can be seen in FIG. 13A. The significance of the linearregression models and their coefficients grows over the four-week timecourse of the experiment, with those experiments in the fourth weekhaving the greatest significance. This trend parallels the very similarincreasing significance of the better and improving MARD values of theAdv-VEGF-A injected mice as compared to the other treatment groups, overthe same four week time course, as seen in FIG. 8. Assuming thatAdv-VEGF injections are efficacious, these two trends match the resultsone would expect from the timing of the injections, which occurredaround the end of the first week, i.e. days 6, 7, and 8. As seen in FIG.13A, we observe that the statistical significance of the linearregression models and their coefficients, is not significant during thefirst and second weeks (p=0.442 and 0.111, respectively), but becomestatistically significant in weeks 3 and 4 (p=0.018 and 0.005,respectively), and consistently grows throughout the four-weekexperimental time course.

Example 1H—Combined Linear Regression Model with Both Blood and LymphVariables

Simple linear regression analysis was then conducted to determine thecontribution of both blood and lymph vessel density to glucose sensorfunction. Reduction in average Mean Absolute Relative Difference (MARD)values represents an improvement in glucose sensor function. Quantifiedincreases in both blood and lymph vessels, as measured in percent areaas blood or lymph vessel, were determined to decrease MARD values by theratios described above, and therefore improve glucose sensor function.The results are tabulated for all data combined (total) and cumulativeone, two, three, and four weeks only, i.e. all those mice that surviveinto the first, second, third, and fourth weeks respectively.

FIG. 13D provides a simple linear regression analysis to determine thecontribution of both blood and lymph vessel density to glucose sensorfunction. Reduction in average Mean Absolute Relative Difference (MARD)values represents an improvement in glucose sensor function. Quantifiedincreases in blood vessels, as measured in percent area as blood vessel,are determined to decrease MARD values by the ratios in the table above,and therefore improve glucose sensor function. The results are tabulatedfor all data combined (total) and cumulative one, two, three, and fourweeks only, i.e. all those mice that survive into the first, second,third, and fourth weeks respectively. The significance is expressed asp-values with statistical significance achieved at p<0.05. R² representsthe correlation between MARD and both the percent area as blood vesseland percent area as lymphatic vessel variables, as per this linearregression model.

As seen in FIG. 13D, for those mice among all treatment groups thatsurvived the entire four week time course of the experiment and whoseblood and lymph vessel density around the sensor was measured, afunctional improvement of 7.13+/−4.74% decrease in MARD for every 1%increase in blood vessel area, and a 1.28+/−2.59% decrease in MARD forevery 1% increase in lymph vessel area was observed. This ratio wasstatistically significant with a p-value of 0.03 and had a correlationR² value of 0.40. In addition, a trend in the significance of thepositive relationship between increased percent area as blood and lymphvessel and improved sensor function can be seen in FIG. 13A. As seen inFIG. 13D, it was observed that the statistical significance of thelinear regression models and their coefficients, is not significantduring the first, second, and third weeks (p=0.321, 0.293, and 0.068respectively), but becomes statistically significant in week 4(p=0.030), and consistently grows throughout the four-week experimentaltime course. R² represents the correlation between MARD and both thepercent area as blood vessel and percent area as lymphatic vesselvariables, as per this linear regression model was 0.40, approximatelythe same as for the linear regression model for MARDs with the bloodvessel variable alone.

Example 2—Basement Membrane Coating for Glucose Sensors

In order to develop a protocol for matrix coating of glucose sensorsthat would allow a simple in vivo sensor implantation a coating anddrying protocol was developed for coating the glucose sensors. In thisExample, modified Abbott Navigator sensors were used. FIG. 14 containsphotographs depicting cell culture derived basement membrane (MATRIGEL®)coating of Abbott Navigator sensor tip combined contribution(s) ofH-Angio and L-Angio to this enhanced CGM seen in Adv-VEGF treatment ofthe implantation sites.

The addition of MATRIGEL® basement membrane to the Navigator sensorsresulted in a simple “jelly-like” coating around the sensor (FIG. 14A).To assure that the MATRIGEL® basement membrane coating would stayassociated with the sensor during sensor insertion, the MATRIGEL® coatedsensor was air-dried overnight (FIG. 14B). The basement membrane coatingon the sensors was then re-hydrated with H₂O (FIG. 14C). The MATRIGEL®basement membrane dried as an even coating, and was also able to rapidlyre-hydrate. The rapid re-hydrating of the dry MATRIGEL® on the sensorprovided significant biocompatibility and a protective barrier aroundthe implanted sensor, and also provided a flexible tissue responsemodifier delivery system. It should also be noted that with multi ECMlayers involving coating and dehydrating there can be a significantaccumulation of salt in the dried basement membrane. The finalrehydration and drying cycle allows for removal of the excess salts fromthe multi-coated MATRIGEL®, which may otherwise be toxic to the tissue.

Example 3—Impact of Basement Membrane on Glucose Sensor Function In Vivo

Once it was determined that MATRIGEL® does not adversely affectfunctionality and sensitivity of the sensor in vitro (FIG. 15), theeffect of MATRIGEL® on sensor function in vivo was then determined (FIG.16). For that, 15 ul of MATRIGEL® (growth factor enriched) were added tothe tip of the sensor and allowed to dry and then implanted aspreviously described. Sensors were implanted in the presence(MATRIGEL®+sensor) or absence (buffer+sensor) of MATRIGEL®. Immediatelyafter sensor implantation, continuous glucose monitoring (CGM) wasinitiated using the mouse system. Sensor accuracy was further evaluatedby calculation of the MARD. Non-MATRIGEL® treated sensor had MARD valuesof 11.3% for the period up to 4 DPI and 38.0% for the CGM period of 4 to14 DPI (FIG. 16A). The significant increase in the MARD value fornon-MATRIGEL® treated sensors was also reflected by the fluctuatingsensor response not correlating with blood glucose levels (FIG. 16-A).MARD value for MATRIGEL® treated sensor ranged from 7.6% to 6.6% for thetesting period up to 4 DPI and 4 DPI to 14 DPI, respectively (FIG.16-B). It is believed that MATRIGEL® likely enhances sensor performanceby protecting the sensor from biofouling.

In summary, these studies demonstrate that a bio-active membrane such asMATRIGEL® can dramatically enhance sensor function in vivo. Thesestudies also support the hypothesis that the uses of bio-matrices suchas basement membrane increase the in vivo lifetime of an implantableglucose sensor. It should be noted that the data in FIG. 16 iscompressed and as such the sensor response might appear as noisysignals. This is only an artifact of the presentation of the data overthe 14-day time frame and due to the many data points obtained over thistime frame (e.g. 1 data point/minute). Although the animals are notdiabetic in these studies the mouse glucose level is still not stagnant(range for normal glucose level is 80-120 mg/dL) and the waves ofglucose excursion can appear as noisy.

Example 4—Coating Glucose Sensors with Basement Membrane

In order to determine capability of layers of matrices on our sensors, 5ul of 10 mg/ml MATRIGEL® was added to the tip of a biosensor (AbbottFreestyle Navigator). Prior to MATRIGEL® addition and immediatelyfollowing MATRIGEL® addition, sensors were tested in a 113 mg/dLbuffered glucose solution. Additionally, the sensors were tested 12hours post-MATRIGEL® addition. For that, MATRIGEL® was added to sensortips and allowed to dry overnight. Sensors containing matrix MATRIGEL®was allowed to re-hydrate for 30 minutes prior to testing in bufferedglucose solution. It was found that sensor sensitivity remainedunchanged in any of the tested conditions for both Nafion coated andAbbott Navigator sensor. To verify that MATRIGEL® remains on the sensortip rather than being stripped off once submerged in buffer or whenadding additional MATRIGEL® layers, pictures were taken at variousMATRIGEL® coating stages utilizing a dissecting microscope connected toa camera. FIG. 14A shows the sensor tip with the addition of 5 ul ofMATRIGEL®. FIGS. 14B and 14C shows the sensor tip after overnight dryingof MATRIGEL® on sensor tip and with re-hydration of MATRIGEL® in H₂O,respectively.

Example 5—Effect of the Basement Membrane on Glucose Sensor Function InVitro

To determine if matrix MATRIGEL® is a physical barrier to glucosediffusion, the in vitro response of glucose sensors was determined withand without MATRIGEL® coating. For these studies, glucose was added tothe sensor (with or without MATRIGEL®) after stabilization of thesensors in phosphate buffered saline (PBS), and sensor response wasfollowed (FIG. 15). Next, the sensor was removed from the PBS/glucosesolution, washed in PBS and then a MATRIGEL® coating (10 mg/ml) wasadded to the working electrode of the glucose sensors. Afterpolymerization of the MATRIGEL®, the glucose sensors were retested at37° C. as described above. Representative results are presented in FIG.15, in which S_(r) indicates the sensor response (e.g. sensor drift) andt_(sd) indicates sensor delay. For these studies it was assumed thatglucose addition to PBS resulted in a homogenous solutioninstantaneously (time delay=0). As can be seen in FIG. 15A there was nosignificant difference in the S_(r) or t_(sd) when we compared theMATRIGEL® coated (FIG. 15B) versus sensors without MATRIGEL® (FIG. 15A)coatings. This preliminary data supports the previous in vitro and invivo data that supports the use of matrices such as MATRIGEL® inenhancing sensor function.

Example 6—Impact of Basement Membrane on Glucose Sensor Function In Vivo

The effect of MATRIGEL® on sensor function in vivo was determined. Priorto implantation sensors were treated with MATRIGEL®. For that, 5 ul ofMATRIGEL® (growth factor enriched) were added to the tip of the sensorand allowed to dry. Two additional MATRIGEL® coatings were added to thesensor with drying steps between each step. Sensors were implanted theday following MATRIGEL® treatment. Sensors were implanted in thepresence (MATRIGEL®+sensor) or absence (buffer+sensor) of MATRIGEL®.Immediately after sensor implantation, continuous glucose monitoring(CGM) was initiated using the mouse system. Glucose-derived current datawere obtained at 60-sec intervals. Blood glucose reference measurementswere obtained periodically over the 14-day implantation period, usingblood obtained from the tail vein (˜0.3 uL) and a FreeStyle BloodGlucose Monitor. First CGM of non-MATRIGEL® treated sensors implanted innormal mice (CD-1) was evaluated. As can be seen in FIG. 16A, sensoroutput only shows one sensor drift at around day 3 in the first 6 DPI.However, at approximately 1-week post implantation the sensorexperienced a sharp decline in sensor performance. Although a sensorsignal is still being measured, it appears to be more random and it doesnot reflect the glucose level of the mouse (FIG. 16A). Alternatively,sensors treated with MATRIGEL® prior to implantation performedexceptional during the entire 14-day testing period (FIG. 16B).Specifically, blood glucose levels for both sensors implanted in themice generally ranged from 80 to 150 mg of glucose/dL of blood, with CGScurrent ranging from 1 to 9 nA for non-treated MATRIGEL® sensors and 4to 8 nA for MATRIGEL® treated sensors. It appears that MATRIGEL®enhances sensor performance by both protecting the sensor frombiofouling as well as protecting the tissue surrounding the sensor fromtissue toxic factor released from the sensor (H₂O₂ and gluconic acid).In summary, these studies clearly demonstrate that MATRIGEL® candramatically enhance sensor function in vivo. These studies also showthat the uses of bio-matrices such as MATRIGEL® with glucose sensors,dramatically increases the in vivo lifetime of an implantable glucosesensor.

Example 7—Usage of “Dry” Bio-Matrices to Deliver Adenovector Genes InVitro

GFP-adenovirus was used as a gene transfer marker and indicator cellsA375 to determine the ability of air dried/4° C. bio-matrices to releasefunctional adenovirus. For these studies GFP-adenoviruses were added tobuffer, MATRIGEL® (10 mg/ml) or collagen (0.1%) at varying finalconcentrations (i.e. serial dilutions). 200 ul of each of the resultingsolutions were added to individual wells of a 24-well plate and allowedto dry overnight at 4° C. The next day A375 indicator cells were addedto each of the wells and allowed to adhere and were cultured overnightat 37° C. and 5% CO₂. As can be seen in FIG. 17A, C, E bright fieldphotographs A375 cells were viable 24 hr post seeding to the wells.Additionally, under all conditions A375 cells were bright green whenviewed under fluorescence microscopy (FIG. 17B, D, F), indicating thatunder all conditions adenovirus were viable and successfully transferredthe GFP gene to the A375 cells. If the GFP adenoviruses were not viableafter drying, the A375 cells would not have turned green underfluorescence microscopy. Analysis of the serial dilution results ofthese studies also indicated that the GFP-Adenovirus were 10-100× timesmore viable when GFP-adenovirus were dried in the presence of MATRIGEL®or collagen when compared to drying in buffer only. These studiesclearly support the concept that drying adenovectors in the presence ofbio-matrices preserves virus infectivity. Thus, this supports the ideathat “dry” adenovector-bio-matrices can be used to locally deliver genesthat are important in controlling TRT at sites of sensor implantation.We anticipate that if we utilize lyophilization to dry matrices we willlikely get even greater adenovector gene transfer, when compared toair-drying.

Example 8—Uses of “Dry” GFP-Adenovector/Bio-Matrix Coated GlucoseSensors to Deliver Genes to Cells In Vitro

Since glucose sensors have different coatings than cell culture dishesand also contain glucose oxidase, which releases both H₂O₂ and gluconicacid as breakdown products of glucose, the cell culture studiesdescribed above were extended by coating Abbott Navigator sensors withGFP-Adenovirus/Bio-matrix coatings (MATRIGEL®) and air drying themovernight at 4° C. The resulting Adenovirus/Bio-matrix coated sensors(MATRIGEL® or collagen) were then placed in a cell culture dish, andmedia containing A375 indicator cells were added to the well. As can beseen in FIG. 18A (GFP-adenovector-MATRIGEL® coating) and FIG. 18B(GFP-adenovector-collagen coating), air-drying of the GFP-adenovector inMATRIGEL® or collagen remained functional. This is indicated by theability of the GFP-adenovectors to transfer the GFP to the indicatorA375 cells in vitro. It should be noted that rehydration of theMATRIGEL® by the media causes significant swelling of the dry MATRIGEL®into a small “mound” around the sensor (see FIG. 14 above). SinceMATRIGEL® auto-fluoresces, the rehydrated MATRIGEL® can easily be seensurrounding the sensor in the 10× photomicrographs in FIG. 18A. Thesesensor studies clearly demonstrate that adenoviruses can be dried in thepresence of bio-matrices and remain functional. These studies supportthe feasibility of using dry bio-matrix coatings for local/targeted genetransfer studies at sites of glucose sensor implantation in vivo

Example 9—Genetic Engineering and Gene Therapy Example 9A—EstablishinghCAR Transgenic Mice Colony

To expedite the adenovector studies, hCAR mice were obtained.Lymphocytes are known to have low levels of CAR and as such are notinfectable with adenovectors. In order to confirm that lymphocytesderived from hCAR mice are infectable with adenoviruses, spleen cellswere isolated and infected using an adenovirus carrying the gene forGFP. As expected, spleen cells from hCAR mice were infectable with GFPadenoviruses (FIGS. 19A and 19B), but control spleen cells from C57BL/Jwere not (see FIGS. 19C and 19D).

Example 9B—In Vitro Expression of mVEGF, hVEGF and hHGF by Mouse hCARBM-ECP after Exposure to Adenovectors Containing Genes for AngiogenicFactors (AF)

Once it was established that hCAR derived lymphocytes were transfectablewith GFP adenoviruses, AF expression was determined in bone marrowderived endothelial cell progenitors (BM-ECP) transfected with AFadenoviruses. The AF adenoviruses used for this study were mVEGF, hVEGFand hHGF. The controls for the AF studies were: 1) GFP adenovectors and2) BM-ECP treated with control media (buffer). After transfection withthe viruses or exposure to the control buffer, individual cell culturesupernatants were obtained at various times post exposure. AF Expression(mVEGF, hVEGF and hHGF expression) in these supernatants was quantifiedby ELISA. Control BM-ECP cells were isolated from bone marrow fromnormal (non-hCAR) mice and treated in an identical fashion. BM-ECPisolated form normal mice (i.e. non-hCAR mice) did not produce anysignificant AF under any treatment condition (data not shown).Additionally, buffer and GFP-adenovirus treated hCAR BM-ECP also did notproduce any significant AF in vitro (FIG. 20). Alternatively, hCARBM-ECP exposed to the AF adenovectors produced rapid expression of theAF factors for all the adenovectors (i.e. mVEGF, hVEGF and hHGFtransfected hCAR BM-ECP cells) see FIG. 20. Thus, the GFP and ELISA dataclearly indicate that one can 1) infect ECP cells with adenovirus, and2) that these infected cells clearly produce the specific AF's whenexposed to AF adenovirus vectors in vitro.

Example 9C—hCAR Adenovirus Enhances Infectivity by Adenoviruses andAngiogenic Factor Expression

Previous studies have demonstrated that increased expression of CAR oncell surfaces enhances adenovirus infectivity and resulting geneexpression in cell. To test this possibility hCAR derived ECP wereinfected with adeno-GFP vectors with or without prior exposure to hCARadenovirus. As expected non-adeno-GFP infected cells showed nofluorescence (FIG. 20B), cells infected with GFP-Adv (FIG. 9D) becamefluorescent but cells infected with viruses GFP-Adv then hCAR-Advdisplay a dramatic increase in fluorescence (FIG. 20F). FIG. 20A is thebrightfield control to FIG. 20B. FIG. 20C is the brightfield control toFIG. 20D. FIG. 20E is the brightfield control to FIG. 20F. This dataclearly demonstrated that the hCAR adenovirus is a potent enhancer ofAdenovirus infectivity and gene expression likely as a result ofallowing super infection of the target cells. To extend these studiesthe ability of pre-infection of target cells with hCAR adenovirus wasdetermined in order to determine enhanced angiogenic factor expressionfor these cells. hCAR derived BM-ECP were treated with 1) buffer, 2)GFP-adenovirus, 3) HGF-Adenovirus or 4) hCAR-adenovirus followed byexposure to hHGF-adenovirus. hHGF expression was only detected in thehHGF infected BM-ECP cells (FIG. 21). Cells infected withhCAR-adenovirus plus hHGF-adenovirus displayed a 3 to 5-fold higher hHGFexpression when compared to the hHGF-adenovirus infected cells. The peakhHGF production by hCAR-hHGF cells in vitro was 48 hrs post infectionswith 15.2 ng/hHGF/ml versus 2.8 ng/hHGF/ml for hHGF cells not previouslytreated with hCAR (FIG. 21). No hHGF protein production was seen incells treated with buffer or GFP (FIG. 21). The ELISA data clearlyindicates that BM-ECP cells treated with hCAR in addition to hHGFsignificantly enhances angiogenic factor expression.

Example 10—P39 Adenovirus Enhances Angiogenic Factor Expression

To determine whether PR39 adenovirus is able to enhance angiogenicfactor expression, i.e. VEGF, human A375 cells were treated with buffer,GFP-adenovirus or PR39-Adenovirus, and VEGF expression determined byELISA analysis of the resulting cell culture supernatants. Since A375cells are human cells, they naturally express low levels of VEGF atbaseline (buffer) and control (GFP-adenovirus) (FIG. 22). However, A375cells infected with adenovirus carrying gene for PR39 significantlyenhanced hVEGF expression by 2.7 fold 24 hours post infection, 6.1-fold48 hours, and 9.1-fold 72 hours post infection with PR-39. The peakhVEGF production in vitro was 72-hours post infection and 4.8ng/hVEGF/ml versus 0.5 ng hVEGF/ml in A375 cells treated with eitherbuffer or GFP (FIG. 22). The data clearly indicate that PR39 can induceVEGF expression in cells likely by inducing the HIF-1a pathway resultingin expression of the potent angiogenic factor VEGF.

Example 11—HCAR Adenovirus Plus P39 Adenovirus Enhances AngiogenicFactor Expression in Mouse Fat Cells

For these studies, mouse fat cells were plated at identical numbers (10⁶cells/well) and incubated with the various Adv of buffer for 24 hr.,then the cells were washed and fresh media was added. At 24, 48 and 72hr. post incubation the culture media was removed and assayed for mouseVEGF by ELISA. As can be seen in FIG. 23A the mVEGF-AdV inducedsignificantly higher mVEGF expression (Approximately 200 pg/ml by 72hrs.), where the levels in both GFP-AdV and buffer treated cells wasvirtually undetectable (FIG. 23C). The results of these studies clearlydemonstrate PR-39-peptide AdV to induce mVEGF expression (Approximately200 pg of mVEGF/ml by 72 hrs.), in the mouse fat cells (FIG. 23B).Finally, since cells that carry the AdV receptor CAR (see background)can not only be infected by Advs but with increased expression of CARcan be super-infected by multiple Advs. Therefore, we determined that iffat cells are pre-infected with Adv that expresses hCAR that we wouldget higher expression of hCAR on the surface of the cells which wouldallow even greater infection by another AdV, i.e. PR-39. As can be seenin FIG. 23C, pre-incubating the mouse fat cells with the hCAR Advresulted in a super induction of mVEGF in the same mouse fat cells (i.e.nearly 800 pg of mVEGF/ml of media), nearly 4 times the levels of mVEGFinduced by mVEGF-Adv or PR-39-AdV alone (FIG. 23C). Combined mVEGF-AdVplus PR-39 AdV mVEGF expression levels seen in FIG. 23C, were over twicethe additive levels of mVEGF-AdV plus PR-39-AdV thus supporting thepossible synergy in gene expression when hCAR expression is induced oncell surfaces. Thus, hCAR-AdV can be used in combination with other AdVto enhance gene expression directly in vivo or as part of geneticallyengineering cells in vitro for in vivo use.

Prophetic Example 12

Fibronectin (FN) can be used as a crosslinking agent for extracellularmatrix (ECM) such as basement membranes and collagen to hold thebasement or collagen together (make ECM stronger). FN can be firstcoated on the device (acting as an adhesive), and then ECM can be addedto stick the ECM to the devices more tightly/stronger. FN can be addedas a coating at any stage of the coating process and even can be usedduring one of the hydration steps in the form of a solution. FN can beused as an adhesive between layers with or without hydration steps.

Drying steps with FN and other ECM are believed to increase thecrosslinking of FN to ECM. Also the drying step can increase thetightness by which additional factors such as cytokines, chemokines,growth factors and inhibitors of inflammation and fibrosis (CGFI) bindto the FN and the other ECM present in the coating layers

Because of the ability of FN to bind various peptides and proteins, itcan be utilized as a drug delivery system when it is added into theextracellular matrix. For example, FN can be added to basement membranescontaining factors, and then the factors are released from the ECM inorder to benefit the surrounding tissue, such as by inducing vesselformation, suppressing inflammation and suppressing fibrosis.

It is believed that the “dry” matrices may actually be more efficient inretaining proteins and peptides (i.e. slower release kinetics) whencompared to the “wet” matrices. Factors such as cytokines chemokines,growth factors antibodies recombinant proteins as well as inhibitors ofinflammation and fibrosis can be cross-linked directly to the matrixusing a cross-linking agent. Factors also can be indirectly crosslinkedto the extracellular matrix using fibronectin or fibronectin relatedpeptides that bind to fibronectin (i.e. fibronectin binding domains orpeptides fragments of fibrin, collagen or RGD peptides). The fibronectinmolecule or fragments act as a bridge to link the various CGFI to thevarious bioactive matrices (see FIG. 25).

Additionally, CGFI often bind to matrices as a mechanism for long-termlocalization of these factors in tissue sites (e.g. wounds and ulcers).Generally, these bound factors interact directly with cells that are incontact with the matrix itself. This solid phase activation of cells isfrequently referred to, as “you are what you sit on.” It is believedthat having rapidly releasing factors (e.g. anti-inflammatory) workingtogether with slow releasing or bound factors is beneficial to controldelayed tissue reactions such as fibrosis and neovascularization.

It is believed that rapidly releasing anti-inflammatory factors such asIL-10, IL-1 ra, and sTNFR are useful in stopping inflammation, where asanti-fibrotic agents such as P144, sTGFR or anti-CD40 are most useful ina delayed release or even remain bound to the matrix, therebyinactivating in-fluxing fibroblasts and suppressing fibrosis.Additionally, late releasing angiogenic factors are expected to beuseful in promoting angiogenesis at a later time frame, i.e. after theinflammatory reactions. Factors such as hepatocyte growth factor (HGF)have an impact on the tissue reaction triad (TRT) of inflammationfibrosis and vessel regression at sites of sensor implantation shown bysuppressing both inflammation and fibrosis, as well as promotingangiogenesis. It is believed that the 2-peptide systems (PR39 and P144)have a significant impact on TRT related cell activation. The releaseprofiles for the various factors under both wet and dry preparation isdifferent. It is expected that the dry protocols will result in matricesthat bind larger amounts of factors and retain them for longer periodsonce they are dehydrated.

It is known that a number of factors can exert their biological actionwhen incorporated into MATRIGEL®, collagen or fibrin e.g. VEGF, FGF,PR39. It is expected that as the concentration of the individual matrixis increased, its total binding capacity also increases, and its rate offactor release decreases. MATRIGEL® (BD Biosciences) is expected to be aparticularly effective wet or dry matrix for these embodiments. Each ofthe component matrices of MATRIGEL® has specific binding sites fornumerous factors and receptors (either on cells or free as solublereceptors). It is expected that fibrin matrix is particularly effectivein delivering factors that control inflammation (IL-10, IL-1ra andsTNFR) and fibrosis (e.g. P144, sTGFR, anti-CD40 and HGF). It isexpected that a mix of MATRIGEL® plus fibrin with the various factorsprovides a good combination of matrix strength with a wide range ofbinding capacities for the various candidate factors (see FIG. 25). Theaddition of fibronectin to the MATRIGEL®-Fibrin combination matrix wouldadd even more tensile strength as well as additional diversity of factorbinding capacity.

In one embodiment, the various CGFI are either coupled tocollagen/fibrin heparin or integrin binding peptide sequence (RGD)peptides using commercial cross-linkers (Pierce Chemical) and then addedto fibronectin, which in turn will bind the CGFI-peptide complex (FIG.25). The CGFI-peptide fibronectin complex is then added to MATRIGEL®,fibrin and or collagen, to which it binds (FIG. 25). The resultingCGFI-peptide-fibronectin-matrix complexes are used in vivo to establisha very controlled distribution of the CGFI with the matrix. Sincefibronectin has both COOH and disulfide cross-linking the CGFI it can bechemically cross-linked thru these residues (FIG. 36). Because CGFInormally interact in vivo with the various bio-matrices used it isextremely likely that all the factors will be functionally active. Thekinetic of release of the various factors must also be considered inchoosing the appropriate combinations. Generally, one would expect thatrapidly releasing anti-inflammatory factors such as IL-10, IL-1ra, andsTNFR would be useful in stopping inflammation, while anti-fibroticagents such as P144, sTGFR or anti-CD40 would be most useful if theyshowed delayed release or even remain bound to the matrix, therebyinactivating in-fluxing fibroblasts and suppressing fibrosis.Additionally, late releasing angiogenic factors would likely be usefulin promoting angiogenesis at a later time frame, i.e. after theinflammatory reactions.

It is expected that the dry protocols will result in matrices that bindlarger amounts of factors and retain them for longer periods once theyare dehydrated.

FIG. 25 is a diagram of the FN molecule with its distinct “backbone”(102), showing ways in which FN can bind with a variety of matrices(104-110) and factors (122-130) at specific binding sites within the FNstructure. The ability of FN to bind matrices such as basement membrane,fibrin, collagen etc. (104-110) allows FN to be an effective biologiccrosslinking agent. Since FN has a specific binding site for heparin, itcan also bind a number of factors that are tissue response modifiers,such as VEGFs that induce new vessel formation in injured (TRMs). Thisbinding can be the result of the structure of the molecule such asheparin (110) or through common peptide sequences such as integrinbinding peptide (RDG) sequences (108). Additionally, various peptidesknown to bind to FN can act as a bridge or crosslinking agent (126).

Additionally, other peptides and various chemical crosslinking agents(114 and 116) can bind factors such as cytokines, growth factors andinhibitors to the FN backbone. Alternatively, because FN has reactiveelements such as sulfhydryl's (118) and COOH groups these can bederivatives to allow covalent linking of various TRMs to the FNmolecule. Ultimately, with the degradation of FN in vivo a wide varietyof TRMs will be released from the FN derivatives.

It should be noted that the modified FNs described above will have atleast one modification per FN molecule, and can be used individually orin any combination or ratio of modified and/or unmodified FNs.

Embodiments of FIGS. 26-37

FIG. 26A shows a sensor assembly with a collar. The sensor assembly 400includes electronics 402, a sensing element support 406 with a sensingelement at the tip 408. The sensor is covered by a polymer to preventinflux of interfering substances into the sensor sensing element 404.When a sensor is implanted into the skin as shown in FIG. 26C, itcreates an open wound 410 with a risk of infections 412 as well asdampness to the upper skin cell layers (e.g. epithelial cells). For thesensor in FIGS. 26B and 26D, the sensing element support 406′ has anantimicrobial collar 414 configured to be positioned on both sides ofthe point at which the support enters the tissue 410. A coating 412containing no additives, or tissue response modifier, such as thoselisted above, can be included within the collar or disposed between thecollar 414 and the sensing element 406′. This configuration preventsinfection and inflammation that otherwise may occur, as shown in FIG.26C, within the tissue around the sensor and support due to, e.g.,bacteria 413. While the coating 414 usually is rehydrated (see 430)after implantation to minimize discomfort to the patient, the coating422, 428, 432 on the coated sensor (416, 418 and 420 in FIG. 26B) alsocan be rehydrated before implantation. In embodiments, the coating canbe applied immediately before assembly, in which case initialdehydration would not be required.

FIG. 27 shows the rehydrated version of the sensor assembly 450 with thecoating 452,454 completely surrounding the implanted portion of thesensor assembly 450. In this embodiment, there are no additives added tothe collars or sleeves, but the collars 452 and sleeves 454 act here asmechanical plugs to prevent infection and “shock absorbers” to preventtissue damage as a result of mechanical movement of the implanted sensorin the skin. Generally, the collars and sleeves are dehydrated prior toimplantation for ease of implantation for the patient and the clinician.The collars and sleeves can be hydrated pre sensor implantation ifadvantageous. In this embodiment, both a collar and sleeve coating areincluded in this compound device and are shown in hydrated form as 458and 460, respectively.

FIG. 28 shows that ECMs with and without anti-microbial agents and TRMscan be incorporated into the ECM collars 502 and sleeves 504 as part ofthe cycles of coating, dehydration, rehydration and dehydration. Whenhydrated pre or post sensor implantation the anti-microbial agentsand/or TRMs are released for the hydrated collars 508 and sleeves 510and control infection inflammation, wound healing and fibrosis at theimplantation site.

FIG. 29 shows that TRMs can be incorporated into the collars 552 andsleeves 554 pre-implantation. This incorporation can induceproliferation of skin surface cells 562 or blood vessels 564 to overcometissue damage at the implantation sites. As such, sensor function ismaintained or even enhanced due to maintaining tissue integrity and ingrowth of blood vessels, which assures real-time blood glucosedetermination by the glucose sensor.

FIG. 30 demonstrates that multiple anti-microbial agents and TRMs can beincorporated in the collars and sleeves to achieve maximal positiveimpact on preventing infection, tissue trauma, inflammation, and inpromoting wound healing and neovascularization. Dehydrated collar 602 ishydrated to form hydrated collar 608. Dehydrated sleeve 604 is hydratedto form sleeve 616. As with the embodiment of FIG. 29, this can induceproliferation of skin surface cells 610 or blood vessels 614 to overcometissue damage at the implantation site.

FIG. 31 demonstrates that collar length can be extended to maximizeanti-microbial and TRMs delivery at the implantation sites to variousdepths in the tissue. This also demonstrates that the collars 652(hydrated at 656) can be extended into the tissue, not just on thesurface to maximize the mechanical “plug” effect and thereby decreaseinfections as well as mechanical damage to the upper layers of the skin.This extended collar assures continuity from the surface of the implantsite into the depth of the implanted tissue.

In embodiments, an extended collar has a length of 2 to 50 mm, or 5-20mm, or 2-10 mm. The diameter at the larger end of the plug typically isin the range of 3-20 mm, or 5-15 mm, or 5-10 mm. In embodiments, acollar that is not “extended” has a length of 2-10 mm, or 2-7 mm, or 3-5mm. The diameter at the larger end of the plug typically is in the rangeof 3-20 mm, or 2-7 mm, or 3-5 mm.

FIG. 32 demonstrates the impact of placement of a collar 704 around aninfusion cannula 702 with and without additives. This cannula with acollar can be hydrated pre or post implantation, and provide a wound“plug” 710, 712 to prevent infection and tissue trauma. The addition ofvarious antimicrobial agents and TRMs further prevent infection,inflammation and fibrosis and promote healing of the implantation sitesboth at upper layers (epithelial lay) as well as the dermis andsubcutaneous tissue.

FIG. 33 shows an infusion system with an infusion pump 752 having tubing754 connected to an infusion set housing 756, which includes an insulinsupply/reservoir (usually to seal tube 758) frequently there is an inertcannula support (758 and 760) as well as an adhesive strip 762. Thisconfiguration does not include a collar. In FIG. 34, a one-piececollar-sleeve combination 810 is disposed on the outer surface of thetissue 814 in which the cannula is implanted. Again, an adhesive strip812 holds the cannula in place on the outer surface 813 of the tissue814. The infusion set cannula is inserted into the skin using a needle(which is inside the cannula) to pierce the skin, thereby allowing thecannula to move into the underlying skin layers using minimal force.Once implanted, the needle is removed and the infusion set is connectedto the pump via a long plastic tubing. Once the tubing is connected tothe infusion pump fluids can be infused into the tissue or vessel asneeded.

FIGS. 35-36 show photographs demonstrating the application of coatingsin accordance with embodiments described herein. The method is describedabove in connection with sensors.

FIG. 37 describes the procedure to multi-coat surgical meshes that areused in reconstructive surgery including hernia surgery. For thisprocedure, surgical mesh (902 and 904) is obtained from a medical supplyhouse, sterilized and placed in sterile containers. The mesh issuspended in a laminar hood to assure sterility. Next the mesh is dipcoated by immersion in ECM, in this case in basement membrane(MATRIGEL®) solution and suspended in the laminar flow hood to allowdrying 906. The BM coated mesh is next allowed to dry, followed byrepeated cycles of addition of BM and drying (907 and 908). After atleast 1 cycle (in this case shown in the photographs there were 10cycles of coating and drying), the coated mesh was rehydrated 918 inwater to remove accumulated salts 920 and then allowed to dry 922. Itshould be noted that the coating not only covers the mesh fibers 910 butalso fills the mesh pores 912, 914. Filling these pores likely willincrease the biocompatibility of the surgical mesh when implanted invivo. After drying, the coated mesh can be directly implanted in apatient or animal who need this type of mesh, or it can be rehydratedand then implanted in vivo.

Modified Basement Membrane Preparations

In embodiments, salts, glucose, individual amino acids, vitamins, andother low molecular weight components can be removed from the basementmembrane to form a modified basement membrane preparation before it iscoated on the device. These components can be removed from the basementmembrane-media combination by a suitable technique depending upon thesize of materials to be removed. Techniques for removing the lowmolecular weight materials include, but are not limited to; dialysis,buffer exchange, diafiltration, precipitation, gel filtration, affinitychromatography and electrophoresis. If this type of process is used, itis not necessary to rinse the basement membrane at the time ofrehydration. Depending on the final use of the basement membrane, theseparation technique can involve a suitable molecular weight cut-off. Inembodiments, this cut-off might be 2000 daltons, or 10,000 daltons, oranother value.

In this embodiment, the dehydrated modified basement membrane can berehydrated using a liquid injected before or after the basementmembrane-coated device is inserted in biological tissue, or theinterstitial fluid themselves can hydrate the basement membrane.

FIG. 38 is a flow chart showing one embodiment for preparing a modifiedbasement membrane preparation. The steps shown on the flow charts aredescribed below in Example 13.

FIG. 39 shows formulations of two types of media used in making basementmembranes sold commercially. The commercially available basementmembrane are sold in a form in which they have already been placed inmedia, such as, but not limited to RPMI1640 from Sigma Chemical Co. orDulbecco's Modified Eagle's Medium (DME) from Sigma Chemical Co.RPMI-1640 contains inorganic salts, amino acids, vitamins and othermaterials. The inorganic salts include calcium nitrate, magnesiumsulfate, potassium chloride, sodium bicarbonate, sodium chloride andsodium phosphate dibasic (anhydrous). DME contains inorganic salts,amino acids, vitamins and other materials. The inorganic salts includecalcium chloride, ferric nitrite, magnesium sulfate (anhydrous),potassium chloride, sodium bicarbonate, sodium chloride and sodiumphosphate monobasic (anhydrous).

FIG. 40 is a set of photos showing salt crystals in basement membrane.FIG. 40A shows salt crystals after drying when no dialysis is used. FIG.40B shows salt crystals after drying when a single dialysis step isused. FIG. 40C shows a lack of salt crystals after drying when twodialysis steps are used.

FIG. 41 includes photos showing the effect of pre-dialyzed andpost-dialyzed basement membrane on tissue surrounding implanted sensors.

Example 13—Dialysis of Basement Membrane

A commercial basement membrane was obtained in which the concentrationof basement membrane was 10-20 mg basement membrane/ml of media. Themouse basement membrane used in these studies was from Becton DickensonBioscience, sold under the name Matrigel®. The tissue culture mediawhich contained the basement membrane when it was purchased was DME orRPMI1640 from Sigma Chemical Co. According to Sigma Chemical Co., thesemedia typically contain greater than 10-15 mg of salts, glucose, andamino acids (in total) per ml of media.

The basement membrane was dialyzed using the procedures and equipment ofPierce (www.piercenet.com). 2 ml of basement membrane was put in a smallcontainer that had a 2000 dalton molecular weight cut-off membrane asthe bottom wall. This container was placed at the top of a tubecontaining 48 ml of water in order that the membrane was immersed in thewater.

The material was dialyzed a first time using the 2000 dalton molecularweight cut off dialysis membrane for 24 hr. (1/25 dilution) at 4 Deg. C.in water on a platform-type rotator. A portion of the material thenunderwent a second dialysis using a 2000 dalton molecular weight cut offdialysis membrane for 24 hr. (1/25 dilution) at 4 Deg. C, using a tubeof water and the platform-type rotator. A portion of the material thenunderwent a final dialysis with the dilution of BM of 1/625. As aresult, the media (not including the basement membrane) contained 0.016to 0.024 mg/ml salts, glucose and amino acids.

Three separate 20-microliter samples of basement membrane (in the media)from the experiment described in the previous paragraph were placed onmicroscopic slides and dried for 24 hours at 37 Deg. C. The first samplewas not subjected to any dialysis. The second sample was subjected tothe first dialysis only, and the third sample was subjected to the boththe first dialysis and the second dialysis. After drying at roomtemperature, the samples were examined to determine the presence andsize of any salt crystals. The results are shown in FIG. 40. As can beseen in the photographs, a large crystalline conglomerate having adiameter of about 20 mm was present in the first sample that had notundergone dialysis, and the crystal diameters were about 2-3 mm. Thesecond sample had medium-sized salt crystal conglomerates. The thirdsample had no easily visible salt crystals.

As shown in the photographs, the dialysis removed most of the salt fromthe media. It can be assumed that the other materials falling below the2000 dalton molecular weight cut-off also were removed.

Example 14—Coating Sensor with Modified Basement Membrane Preparation

A sample of the modified basement membrane preparation that hadundergone the two-stage dilution described above was coated on a glucosesensor by depositing the basement membrane on a sensor dropwise, threedrops at a time and drying the coating at room temperature. Thisprocedure was repeated until a total of about 100 microliters ofbasement membrane had been deposited. A mesh made of polyester wasseparately coated. A collar for a cannula also was formed from themodified basement membrane preparation.

After the coated sensor was dried for 24 hours, it was placed in thesubcutaneous tissue of a mouse. After 14 days, a histologic evaluationof the implantation site was conducted by euthanizing the mouse,removing the tissue, processing the tissue, and evaluating itmicroscopically. As is shown in FIGS. 41C and 41D, there was minimal, ifany, injury or inflammation of the tissue, with little, if any,degradation of the basement membrane. Because of the dialysis, it wasnot necessary to remove salts, glucose, and amino acids at the time ofrehydration.

A control experiment was conducted using a sample of the basementmembrane (in media—as sold commercially) that did not undergo anydialysis. A glucose sensor of the same type used above was coated in themanner described above. After the sensor was dried for 24 hours, it wasplaced in the subcutaneous tissue of a mouse. After 14 days, ahistologic evaluation of the implantation site was conducted byeuthanizing the mouse, removing the tissue, processing the tissue, andevaluating it microscopically. As is shown in FIGS. 41A and 41B, therewas substantial injury and inflammation of the tissue, as well asextensive degradation of the basement membrane. Degradation of thebasement membrane was caused by proteases and hydrolases from whiteblood cells that dissolve and degrade matrices including basementmembrane.

Example 15

The procedures of Examples 13 and 14 were generally repeated usingcommercially available Trevigen basement membrane called CULTREX®Basement Membrane Extract, Type 2, PathClear® (purified fromEngelbreth-Holm-Swarm (EHS) tumor). The results of salt crystal sizewithout dialysis, after 1 stage of dialysis and after 2 stages ofdialysis were similar to the results of Example 13. Examination of thetissue after 14 days showed the same effects as with the Matrigel®, i.e.tissue inflammation and basement membrane degradation when pre-dialyzedbasement membrane was used, and minimal tissue inflammation and basementmembrane degradation when dialyzed basement membrane was used.

Example 16

In an effort to even further increase the stability and effectiveness ofthe basement membrane coatings, the coatings were cross-linked utilizingglutaraldehyde as a cross-linking agent. Sensor performance wasevaluated for the impact of these crosslinked coatings in vitro and invivo. Sensor performance was assessed over a 28-day time period in amurine CGM model and expressed as Mean Absolute Relative Difference(MARD) values. Tissue reactivity of uncrosslinked basement membranecoated sensors, crosslinked basement membrane coated sensors, anduncoated sensors was evaluated at 7, 14, 21 and 28 days post sensorimplantation with standard histological techniques. These studiesdemonstrated that crosslinked basement membrane coatings had no effecton glucose sensor function in vitro. In vivo glucose sensor performancewas significantly enhanced when the crosslinked basement membranecoatings were used. Histological evaluations of sensors coated withcrosslinked basement membrane demonstrated significantly less tissuereactivity when compared to control sensors.

Basement Membrane Preparations

Basement Membrane Extract (CULTREX®, Type 2) Clearpath, was purchasedfrom Trevigen, Inc. (Gaithersburg, Md.). CULTREX® Basement MembraneExtract (referred to as CULTREX®, CULTREX® basement membrane or CULTREX®BM) is a soluble form of basement membrane purified from murineEngelbreth-Holm-Swarm tumor. The basement membrane is stored inDulbecco's Modified Eagle's medium without phenol red, with 10-ug/mlgentamicin sulfate, at a storage and working concentration ofapproximately 15 mg protein/ml (Table 1). Generally the CULTREX®preparations are kept frozen at −80 C, thawed in ice water, andmaintained on ice for general use.

Dialysis of Basement Membrane Preparations

To eliminate salts, vitamins, amino acids and glucose present in thebasement membrane preparations, the basement membrane was dialyzedagainst sterile deionized water with 3 changes of water using ThermoScientific Slide-A-Lyzer Mini Dialysis devices. More specifically, 2 mlof CULTREX® was dialyzed against 48 ml of water/exchange, for a total of3 dialysis exchanges.

Coating of Glucose Sensors with Cross-Linked Basement Membrane

The modified Abbott Navigator glucose sensors which are TransdermalAmperometric sensors used in the in vitro and in vivo studies wereobtained from Abbott Diabetes Care [Alameda, Calif.]. Sensors weresterilized by exposure to UV light overnight prior to administering thesensor coating. Aseptic techniques were utilized during the coatingprocess and prior to implantation. To coat the glucose sensors withcross-linked basement membrane, the glucose sensors were mounted (FIG.47A) and placed on a sterile polytetrafluoroethylene (PTFE) liner (FIG.47B). Specifically, 50 uL of dialyzed CULTREX® (15 mg protein/ml) wasapplied on one side of each sensor (FIG. 47C) and the sensors wereplaced in a 37° C. incubator for 2 hours, resulting in drying of thebasement membrane (FIG. 47D). The glucose sensors were then turned overand an additional 50 uL of dialyzed CULTREX® was applied on the oppositeside of the sensors (FIG. 47E) prior to placing them in 37° C. incubatorfor 2 hours, resulting in drying (FIG. 47F). The resulting coatedsensors were lifted off of the PTFE liner (FIG. 47G) and briefly dippedinto sterile pyrogen-free water to shape the coating around the sensors(FIG. 47H) followed by drying at 37 C (FIG. 1I). Next the dry coatedsensor was place in a 0.2-0.4% glutaraldehyde solution (FIG. 47J) for 5minutes followed by at least 1 hr of dialysis in sterile, pyrogen-freewater, followed by drying at 37° C. for at least 2 hours (FIG. 47L)Other biocompatible solutions, such as alcohol or buffers, can be usedin place of pyrogen-free water. FIG. 47K demonstrates that even afterbeing cross-linked, the CULTREX® basement membrane preparations arestill gelatinous and full of liquid (i.e. they remain bio-hydrogels).FIG. 47L demonstrates that when the gluteraldehyde cross-linked CULTREX®BM it forms a thin layer of dry BM which enhances both its shelf-life,as well as the ease of inserting the coated sensor into living tissue.The resulting cross-linked CULTREX® was designed as X-CULTREX®. Thiscoating technique allowed for a simple and consistent coating process.The crosslinked coated glucose sensors and the control sensors, some ofwhich were uncoated and some of which were coated with uncrosslinkedbasement membrane, were stored dehydrated in a tissue culture hood untilin vitro testing or implantation in mice.

In Vitro Glucose Sensor Testing

In order to determine if X-CULTREX® coating negatively impacted sensorperformance, sensor sensitivity of uncoated glucose sensors (controls),were evaluated pre and post X-CULTREX® coating in vitro. Sensorsensitivity was characterized in tissue culture medium with an initialglucose concentration of 50 mg/dL at 200 mV. Background current wasallowed to stabilize for about 15 minutes before sensors were subjectedto increased glucose concentrations in the culture medium. Sensors werethen rinsed in sterile water and left in a tissue culture hood to dry.After the sensors completely dried they were coated with X-CULTREX® asdescribed above. Sensors were then retested in vitro using the sameprotocol as described above. Sensor sensitivity for both pre and postX-CULTREX® coatings was determined as described below (2, 5).

Glucose Sensor Implantation and CGM

Once it was established that the sensor coating did not negativelyimpact sensor performance in vitro, the performance of the X-CULTREX®coated sensors versus uncoated sensors was evaluated in a CGM mousemodel. Coated and un-coated sensors were implanted in CD-1 mice (JacksonLaboratory, Bar Harbor, Me.) and continuous glucose monitoring (CGM) wasundertaken for a period up to 28 days. Blood glucose referencemeasurements from the tail vein were obtained systematically over the28-day implantation period using Bayer Contour blood glucose monitors.The Institutional Animal Care and Use Committee of the University ofConnecticut Health Center (Farmington, Conn.) approved the murinestudies. The sensors were not recalibrated such that their readingsrepresent raw sensor output in nano-Amperes (nA).

Continuous Glucose Monitoring Data Analysis

Reference blood measurements were used to calculate the mean absoluterelative difference (MARD) over a four-week experiment for the twogroups of mice with and without basement membrane coated sensors.Equations (1)-(3) describe the MARD calculation in detail. Sensitivity(S; mg/dl/nA) is calculated for each mouse based on the reference bloodglucose and the sensor output (I; nA) measurements in an initialreference stage of the experiment, i.e., k in Equation (2) isapproximately 5, for the first initial five measurements across twodays.

$\begin{matrix}{{{{MARD}({mean})} = {\left( {\left( {\sum\limits_{i}^{n}\frac{❘{{CGM}_{i} - {BG}_{i}}❘}{{BG}_{i}}} \right)/n} \right) \times 100\%}},} & (1)\end{matrix}$ $\begin{matrix}{{{Sensitivity}(S)} = \left( {\left( {\sum\limits_{i}^{k}{\left( {{BG}_{i}/I_{i}} \right)/k}} \right),} \right.} & (2)\end{matrix}$ $\begin{matrix}{{CGM}_{i} = {S \times {I_{i}.}}} & (3)\end{matrix}$Histopathological Analysis of Tissue Reactions at Glucose SensorImplantation Sites

In order to evaluate tissue responses to non-CULTREX® coated, CULTREX®and X-CULTREX® coated glucose sensors tissue samples were obtained frommice concluding CGM evaluation. Mice were euthanized and the fullthickness of the skin and sensors were removed end bloc in approximately3×3 cm² sections and immediately placed in tissue fixative. Tissues werefixed in formalin for 24 to 48 hours followed by processing, embeddingin paraffin, and sectioning. The resulting 5-μm sections were thenstained using standard protocols for hematoxylin and eosin stain andMasson Trichrome (fibrosis). Histopathological evaluation of tissuereactions at sites of sensor implantation was performed on mousespecimens obtained at 1-28 days post-sensor implantation. The tissuesection slides were viewed and assessed by a blinded experiencedhistopathologist (DLK) using a modified histologic scale (2, 4, 5, 7).Histologic parameters included inflammatory response, foreign bodyreaction, fibrotic response, collagen organization, andneovascularization. After an initial review of all slides to gain abaseline measure of histologic parameters, each sample was re-evaluatedand scored against each other to obtain a semi-quantitative measure oftissue responses to the implanted sensors. For the inflammatoryresponse, the degree of infiltration of chronic inflammatory cells,principally lymphocytes and macrophages, surrounding the sensor werenoted. Foreign body reaction was determined by the relative quantity offoreign body giant cells (FBGC) surrounding each sensor or adjoiningtissue of sensor. Fibrotic change was a function of relative abundanceof new collagen deposition at sites of sensor implantation, whilecollagen organization was determined by factors such as connectivetissue density (loose versus dense) and arrangement of collagen bundles(parallel versus haphazard pattern). Neovascularization was a reflectionof the number of new blood vessels per high power field (7).

Immunohistochemical Staining of Macrophages Using Anti-Mouse F4/80Antibodies

To confirm the observed presence of macrophages in tissue sections, amouse macrophage specific antibody designated anti-mouse F4/80 wasutilized. Anti-mouse F4/80 (@F4/80) (Invitrogen Catalog #A14800) wasvalidated using mouse spleen tissue and standard immunohistochemical(IHC) techniques.

Statistical Analysis

The mean MARD values for each group, together or separated by week, wereevaluated statistically, including tests to determine if the group MARDvalues were normally distributed. In cases where the mean MARD valueswere non-normal in distribution, Mann-Whitney U tests were thenconducted to determine the statistical differences between the twogroups of average mean MARD values, as non-parametric equivalents tostudent t-tests. Microsoft Excel for Mac 2011 (version 14.1.4) and IBMSPSS Statistics 20 (release 20.0.0) were the software packages used forthe calculations/graphing and statistical analyses, respectively.

Results

Impact of CULTUREX® Coatings on Glucose Sensor Function In Vitro and InVivo

Previous experiments have demonstrated that glucose sensors coated withnon-cross-linked CULTREX® did not affect sensor function in vitro (1).Previous experiments also have demonstrated that sensors coated withCULTREX® showed significantly less tissue reaction at sites of sensorimplantation. These CULTREX® coated sensors also showed an increasedperformance compared to uncoated sensors. The CULTREX® sensor coating,however, began to degrade by day 21-post sensor implantation and sensorinduced sensor tissue reactions were seen. It is believed that the lossof the CULTREX® coatings eliminated the protective sensor coatingresulting in the exposure of the underlying sensor surface. In an effortto increase the longevity of the CULTREX® sensor coating, cross-linkedCULTREX® was used to first determine whether cross-linked CULTREX®coating compromised sensor function in vitro (FIG. 47). The impact ofvarying coatings of CULTREX® on glucose sensor performance in vitro wasdetermined, as is described above. Sensor sensitivity remained unchangedbefore and after the CULTREX® coating within the range of 0 to 2 mgCULTREX®/sensor, and was determined to be 45.9±4.8 mg/(dL*nA) and48.6±5.1 mg/(dL*nA), respectively. For the cross-linked CULTREX®(X-CULTREX®), sensor sensitivity remained very close before and afterthe X-CULTREX® coating within the range of 0 to 3 mg X-CULTREX®/sensor,and was determined to be 37.9±3.2 mg/(dL*nA) and 41.3±2.2 mg/(dL*nA),respectively.

Once it had been demonstrated that the cross-linking of CULTREX®coatings did not negatively affect sensor performance in vitro, theeffect was determined of X-CULTREX® coatings on sensor performance invivo for a period of up to 28 days. These in vivo studies were performedutilizing an established murine model of CGM. For these studies meanabsolute relative difference (MARD) values of non-cross-linked CULTREX®and X-CULTREX® coated sensors were used, as well as uncoated, controlsensors in CD-1 mice as a measure of sensor performance and error of theCGM sensors over time; the lower the MARD values, the lower the error,the better the performance. It is important to note that no sensorrecalibration occurred for these studies. Thus, MARD values used inthese studies are derived from raw sensor output. As illustrated in FIG.48, the cross-linking of the CULTREX® on the sensor resulted in asignificant improvement of sensor functionality when compared touncoated or non-cross-linked CULTREX® coated sensors for the entire 28day in vivo evaluation (FIG. 48). Statistical comparisons of the sensorperformance during the entire four week, 28 day post-implantationexperimental time course, showed that the X-CULTREX® had dramaticallybetter MARD values compared to non-coated control and CULTREX® coatedsensors (FIG. 48, and FIG. 52). By the fourth week, the total averageMARD value for the CD-1 mice with X-CULTREX® coated sensors was 10.59%in a group of 26 mice, CULTREX® coated sensors was 16.7% in a group of34 mice, as compared to the CD-1 control mice with 20.52% on average, ina group of 39 mice (FIG. 53). These sample sizes are relatively largefor such investigations. A calculation of standard deviation of the MARDvalues for these groups of mice indicates that the CD-1 controls presenta larger standard deviation of 6.58%, while the CULTREX® coated CD-1MARD values present a smaller standard deviation of 6.14%, and theX-CULTREX® coated sensors with a very low standard deviation of 2.94%(FIG. 53).

It is noted that the overall performance of the X-CULTREX® coatedsensors surpassed sensor performance of CULTREX® and uncoated sensorswithin the first 7 days of the study (FIG. 49). This is important sincethe high accuracy underscores the enhancing effect of X-CULTREX® evenwithin the first 7 days post sensor implantation. The sensor performancein day 1 was significantly improved with the crosslinked basementmembrane when compared to uncoated sensors and sensors coated withnon-crosslinked basement membrane of the same type.

As illustrated in FIG. 48, a trend analysis of the MARD values of theCULTREX® and X-CULTREX® coated sensors in CD-1 mice and their CD-1control mice, over the course of the four (4) week experiment, shows asignificant improvement in sensor performance, i.e. lower MARD values,for the X-CULTREX® coated sensors throughout the entire experiment. Thedifference in MARD values among all three groups was statisticallyevaluated by ANOVA tests and its non-parametric equivalent,Kruskal-Wallis (K-W) tests. The differences in MARD values between anytwo groups were statistically evaluated by student t-tests and itsnon-parametric equivalent, Mann-Whitney U-tests. The MARD values forweeks 1 and 2, required the non-parametric Mann-Whitney U-tests, whileweek 3 and the total mean MARD values were normally distributed, henceevaluated with student t-tests. Total mean MARD values are MARD valuesnot separated by week, i.e. each sensor/mouse has one average or meanMARD value for the entire or total experiment. The MARD values for week4 generally required the non-parametric statistical tests, because theCULTREX® coated CD-1 mice MARD values for week 4 were not normallydistributed. However, both the X-CULTREX® coated and control CD-1 MARDvalues for week 4 were normally distributed, and the statisticalcomparison of those two groups were evaluated with a student t-test. Astatistical comparison among the three groups by total mean MARDrevealed that they were significantly different, p=0.0000. Statisticalcomparisons between each pairing of the three groups by total mean MARDrevealed that all the groups were significantly different from eachother: CULTREX® coated and control CD-1, p=0.0114; CULTREX® andX-CULTREX® coated CD-1, p=0.0000; X-CULTREX® coated and control CD-1,p=0.0000. The statistical comparisons among the three groups by weekdemonstrated that there were significant differences during the entirefour week experimental time course, i.e. p=0.0000, 0.0000, 0.0000,0.0022, for weeks 1 through 4, respectively. The effects of X-CULTREX®in improving sensor performance, even better than simply CULTREX®coating, were clear in the first week (FIG. 3), since the statisticalcomparison between the CULTREX® CD-1 and control CD-1 mice demonstratedthat there was only a trending significant difference, i.e. p=0.0768 inweek 1, whereas there was strong significant difference betweenX-CULTREX® CD-1 and control CD-1 mice in week 1, p=0.0000. As expectedthe uncoated sensors displayed a decrease in sensor performance beyond7-day implantation, and a rise in MARD values, as per the trend analysisgraph. However, the X-CULTREX® coated sensors continued to displaysignificantly better performance over the entire same 28 days of thestudy (FIG. 48), and CULTREX® coated sensors displayed a significantlybetter performance weeks 2 and 3. Particularly in the second week, aMann-Whitney U-test, revealed a statistically significant differencebetween the MARD values for CULTREX® coated sensors in CD-1 mice whencompared to the uncoated sensors implanted in CD-1 control mice(p=0.0058), and the MARD values for X-CULTREX® in week 2 even decreasedrelative to week 1, (p=0.0000). In the third week, a t-test revealedthat the CULTREX® coated sensors showed statistically significant betterperformance compared to CD-1 controls (p=0.0303), while X-CULTREX®coated sensors continued to show very strong performance compared toCD-1 controls (p=0.0000). By the fourth week, although the CULTREX®coated sensors did appear to be out performing the uncoated sensors, theMARD between them was not statistically different (p=0.1774). HoweverX-CULTREX® coated sensors again continued to show very strongperformance compared to CD-1 controls (p=0.0004).

Impact of Basement Membrane Coatings on Sensor Induced Tissue Reactionsat Sites of Glucose Sensor Implantations

Based on the functional data described above, it is evident that thedramatic increase in the sensor performance of the X-CULTREX® coatedsensor was a direct result of the diminished sensor induced tissuereactions in the X-CULTREX® coated sensors, i.e. increasedbiocompatibility and stability of the X-CULTREX® coatings. Previousstudies in our laboratories demonstrated that non-cross-linked CultrexBM preparations (gel form) can be implanted in mouse subcutaneous tissuefor extended periods of time without inducing significant tissuereactions (1). Unfortunately the non-cross-linked CULTREX® begandegrading around 14-21 days post sensor implantation resulting inincreased tissue reactions at the sensor implantation site (1). As such,the biocompatibility of the non-cross-linked CULTREX® in vivo suggestedthat it could be a strong candidate for biocompatibility coating forimplanted devices, such as glucose sensors, if it was more stable andremained highly biocompatible.

To investigate whether cross-linked CULTREX® enhances coating stability,while retaining biocompatibilty, the tissue reactions associated withnon-coated, non-cross linked CULTREX® and X-CULTREX® coated sensorsimplanted in mouse subcutaneous tissue were evaluated over a 28 day timeperiod (FIG. 50). As expected, from the previous studies during thefirst 14 days post sensor implantation, the non-cross-linked CULTREX®appeared intact on the sensor surface and demonstrated significantlyless tissue reaction at the implantation site (FIGS. 50, E and F).However by 21 and 28 days there was significant loss of the CULTREX®coating on the sensor surface and early indication of tissue reactionsbeing induced at the sensor implantation site (FIGS. 50, G and H). Whentissue reactions induced by X-CULTREX® coated sensors, X-CULTREX®demonstrated that X-CULTREX® was very stable and biocompatible for thetested time period up to 28 days post sensor implantation (see FIG. 50,I-T v) when compared the non-cross linked CULTREX® (FIG. 50, e-h) aswell as uncoated sensors (FIG. 50, a-d). To extend these observationsthe presence of macrophages at sensor implantation sites was evaluated.Macrophages were selected because of their clear role in biofouling ofglucose sensors in vivo. For these studies immunohistochemical stainingof tissue section using mouse macrophage specific anti-F4/80 antibodies.As can be seen in FIG. 51, non-CULTREX® coated sensors triggeredsignificant macrophage accumulation at the uncoated sensor implantationsite (FIGS. 51 c and d). Alternatively, coating the sensors withCULTREX® (FIGS. 51 e and f) or X-CULTREX® (FIGS. 51 g and h) resulted ina dramatic decrease in macrophage accumulation at the coated sensorimplantation sites. In conclusion, it is important to underscore thefact that these histologic studies are consistent with the sensorfunction study present in FIGS. 48 and 49, and support our hypothesissupporting the uses of X-CULTREX® as a sensor coating in vivo.

Discussion

It is now generally accepted that glucose sensor's frequent unreliableperformance is often the result of the tissue reaction induced in partby the sensor implant and in part by the initial implantation itself.Over the years various efforts have been examined with the common goalto foster device/tissue integration with minimal to no tissue reactions.These efforts include controlling the tissue reaction at sites of devicelocation with the release of steroids (8-12) and/or growth factors.Recent efforts in our laboratory demonstrated that basement membrane(BM) based bio-hydrogels as coatings (designated as CULTREX®) forglucose sensors enhance sensor biocompatibility and function in vivo.Specifically, these studies showed that CULTREX® based BM sensorcoatings accomplished the dual goals of 1) decreased tissue reactivityat site of glucose sensor implantation in vivo as well as 2) extendeddevice performance in a CGM murine model. Nonetheless theseaccomplishments were short lived due to the degradation of thebio-hydrogel. Upon the initiation of the bio-hydrogel degradation due tothe natural degradation processes related to extracellular turnover asubsequent decline in sensor performance was seen around three weekspost sensor implantation. It is believed that this degradation processexposes the original sensor surface and induces the commonly observedforeign body tissue reaction. As such, the bio-hydrogel was only able todelay the tissue reaction at the sensor implantation site. It appearedthat this delay is dependent on the degradation rate of the outer sensorCULTREX® coating.

In response to these observations the present studies were undertaken toinvestigate whether chemical crosslinking of the CULTREX® would increasethe stability and biocompatibility of CULTREX® based biohydrogels invivo, and thereby increase the function and lifespan of sensors and CGM.Previous studies using cross-linked collagen coatings, demonstratedmarginal effects on sensor function in vivo. This lack of enhancedsensor function was likely due to tissue reactions that were induced bythe cross-linked collagens, i.e. inflammation and fibrosis. These tissuereactions were likely the result of excessive crosslinking of thecollagen by gluteraldhyde. Due to issues of gluteraldehyde inducedtissue reactions, our strategy was to utilize low concentrations ofgluteraldehyde (0.2-0.3%) and only briefly expose BM (i.e. CULTREX®) tothe gluteraldehyde (i.e. 5 minutes) fixative. Upon fixation thesensor/BM gluteraldehyde coating was then followed by exposure topyrogen free water to minimize any tissue induced tissue reactionsresulting from the fixative. In order to minimize effects of thefixative to the tissue, CULTREX® BM was cross-linked upon the completionof post sensor CULTREX® BM coating and drying. In vivo murine CGMstudies demonstrated that X-CULTREX® coated sensors experienced overallvery strong performance compared to CD-1 controls and CULTREX® coatingonly. This strong performance for X-CULTREX® coated sensors was seenbeyond the third week of study. As it relates to CULTREX® coatedsensors, performance in week three and four was increased when comparedto control (e.g. no CULTREX® coating) (FIG. 48). It is believed that theincreased MARD values seen particularly in weeks three and four postsensor implantation of the CULTREX® coated CD-1 mice was likely theresult of the degradation of the CULTREX® coating, a result of thenormal tissue remodeling, which does not appear or only slightly occurin the X-CULTREX® coated sensors (FIG. 48). This hypothesis wassupported by the histologic studies (FIG. 50). This degradationultimately exposes the underlying glucose sensor, triggering the regulartissue reactions including inflammation and tissue remodeling leading tofurther degradation of the CULTREX® coating of the sensors. The use ofglutaraldehyde to cross-link CULTREX® appears to prevent appreciabledegradation and subsequently appears to prevent tissue remodeling andinflammatory processes. Interestingly, X-CULTREX® outperformed CULTREX®coated sensors alone and control sensors also during the first week postsensor implantation (FIG. 49). It is believed that this is due in partto the consistence of the X-CULTREX® coating to stay in place during theimplantation process. It is believed that CULTREX® coating sensorsexperience a higher rate of variability during the implantation processdue to dislocating the CULTREX® coating. Nevertheless, these studiesemphasize that a biocompatible hydrogel such as CULTREX® can facilitatean increased long-term sensor performance.

Natural bio-hydrogels present numerous binding sites for specificproteins such as growth factors and cytokines within their molecularstructures (15-24). These binding sites serve a critical role inregulation of cell and tissue responses to injury includinginflammation, repair and regeneration.

Conclusion—

This example demonstrated that the sensors coated with crosslinkedbasement membrane dramatically enhanced glucose sensor function andlifespan in vivo, and induced virtually no tissue reactions in a 28 daytime period, when compared to non-cross-linked control coatings, andsensors without any coatings. These studies show that crosslinked matrixcoatings such as biohydrogels can be used biocompatible coatings forimplantable devices, such as glucose sensors, and other implantsdescribed above. Crosslinking protocols aid in the enhancement ofbiohydrogel stability and biocompatibility in vitro and in vivo withoutcompromising loss of biocompatibility, i.e. X-CULTREX® BM coatings. Thedata included herein suggest that cross-linked BM based bio-hydorgelsrepresent a completely new generation of biocompatible coatings forimplantable devices such as glucose sensor and a vast variety of otherimplantable devices.

Prophetic Example 17

The procedures of Example 16 are repeated with the exception that theglutaraldehyde is added to the basement membrane before drying, i.e. atthe stage of FIG. 47C, 47E and/or 47H. The glutaraldehyde can be addeddropwise to the wet basement membraned that is already on theimplantable device, or can be pre-mixed with the basement membranebefore the device is coated with the basement membrane. Excessglutaraldehyde optionally can be removed by a suitable technique such asplacement in pyrogen-free, sterile water or another liquid, or by theaddition of glutaraldehyde reactive agents. The resulting crosslinkedcoating is similar to that obtained in Example 16. This techniqueprovides an opportunity for more control of the final concentration ofglutaraldehyde in the coating and may simplify a large-scale production.

Prophetic Example 18

The procedures of Example 16 are repeated with the exception that thebasement membrane is crosslinked with other crosslinking agents. It isexpected that reactive molecules would be cross-linked by variety ofcrosslinking agents, thereby changing the primary, secondary andtertiary structure of the cross-linked basement membrane by changed thecrosslinking agent. In this way the functionality and biocompatibilityof the coating can be altered.

Prophetic Example 19

The procedures of Example 16 are repeated with the exception that thesensor is replaced by a surgical mesh. It is expected that these meshesincrease in their biocompatibility.

Prophetic Example 20

The procedures of Example 16 are repeated with the exception that thesensor is replaced by a cannula and the basement membrane is applied tothe implantable portion of the cannula. It is expected that thisembodiment will result is a lower degree of tissue reaction with moreeffective regulation of blood glucose.

Prophetic Example 21

The procedures of Example 16 are repeated with the exception that thesensor is replaced by a collar for an implantable device and thebasement membrane is applied to the portion of the collar configured tobe adjacent to, or inserted in, tissue. It is expected that thefunction, accuracy and lifespan of the sensor will be increased becauseof a decreased likelihood, rate or degree of infection as a result ofinfection caused by the transdermal device.

Example 22

To determine the stability and reactivity of X-Cultrex coated sensors inmice at time points beyond 28 days, sensors coated with cross-linkedCULTREX® (0.3% glutaraldehyde) were implanted subcutaneously in mice andremoved at 2 months post implantation. When the implantation site wasevaluated in situ significant neovascularization was seen surroundingthe X-CULTREX® coated sensor, specifically at the tissue X-CULTREX®interface (see FIG. 54). Arrows indicate the presence of new bloodvessels in tissue surrounding the X-CULTREX® coated sensor. This studydemonstrates that increased neovascularization surround the X-CULTREX®coated sensor occurs at 2 months post sensor implantation. Thisincreased neovascularization would likely promote sensor function byproviding a blood vasculature close the sensor. The presence of thisvasculature close to the sensor would give a more accurate real timeevaluation of blood glucose in the mice.

It is appreciated that the above-disclosed and other features andfunctions, or alternatives thereof, may be desirably combined into manyother different systems or applications. Various presently unforeseen orunanticipated alternatives, modifications, variations, or improvementstherein may be subsequently made by those skilled in the art, which arealso intended to be encompassed by the following claims. Unlessotherwise specifically defined in the claims, steps and components ofthe examples are not intended as limitations to any particular order,position, size, shape or material.

What is claimed is:
 1. An implantable device coated with a crosslinkedextracellular matrix comprising at least one of Type IV collagen andlaminin, wherein the crosslinked extracellular matrix contains no morethan 0.024 mg/ml total concentration of glucose, amino acids and saltshaving a molecular weight of 2000 daltons or less.
 2. The implantabledevice of claim 1, wherein the crosslinked extracellular matrix isdehydrated after being in the form of a gel at room temperature.
 3. Theimplantable device of claim 1, wherein the crosslinked extracellularmatrix is applied in multiple layers, and the extracellular matrix isdehydrated after application of each layer.
 4. The implantable device ofclaim 1, wherein the crosslinked extracellular matrix contains at leastone of cells and factors, the factors being at least one member selectedfrom the group consisting of angiogenic factors, drugs, antimicrobials,cytokines, growth factors and anti-inflammatory factors.
 5. Theimplantable device of claim 1, wherein the crosslinked extracellularmatrix contains a factor that includes at least one of a vascularendothelial growth factor (VEGF), a hepatocyte growth factor and afibroblast growth factor.
 6. The implantable device of claim 1, whereinthe extracellular matrix is crosslinked with a dialdehyde.
 7. Theimplantable device of claim 4, wherein the cells and/or factors arebonded to the crosslinked extracellular matrix.
 8. The implantabledevice of claim 1, wherein the crosslinked extracellular matrixcomprises cell culture derived extracellular matrix.
 9. The implantabledevice of claim 1, wherein the implantable device comprises at least onemember selected from the group consisting of sensors, meshes, stents,and cannulas.
 10. A kit comprising the implantable device of claim 1enclosed in sterile packaging.
 11. The implantable device of claim 1,wherein the implantable device comprises a sensor.
 12. The implantabledevice of claim 11, wherein the crosslinked extracellular matrixcontains at least one of cells and factors, the factors being at leastone member selected from the group consisting of angiogenic factors,drugs, antimicrobials, cytokines, growth factors and anti-inflammatoryfactors.
 13. The implantable device of claim 11, wherein the crosslinkedextracellular matrix contains a factor that includes at least one of avascular endothelial growth factor, a hepatocyte growth factor and afibroblast growth factor.
 14. The implantable device of claim 11,wherein the extracellular matrix is crosslinked with a dialdehyde. 15.The implantable device of claim 1, wherein a synthetic matrix materialis combined with the crosslinked extracellular matrix.
 16. Theimplantable device of claim 1, wherein the crosslinked extracellularmatrix contains at least one member selected from the group consistingof anti-fibrotic agents, factors that promote angiogenesis and factorsthat promote lymphangiogenesis.
 17. The implantable device of claim 1,wherein the crosslinked extracellular matrix contains at least one ofnatural fibers and synthetic fibers.
 18. The implantable device of claim1, wherein the crosslinked extracellular matrix contains at least onegenetic element selected from the group consisting of DNAs, RNAs, viralvectors and plasmids.
 19. The implantable device of claim 1, wherein thecrosslinked extracellular matrix contains at least one of siRNA,genetically altered RNA and chemically altered RNA.
 20. The implantabledevice of claim 1, wherein the crosslinked extracellular matrix containscells.
 21. The implantable device of claim 1, wherein the crosslinkedextracellular matrix contains at least one of VEGF-A, VEGF-B, VEGF-C andVEGF-D.
 22. The implantable device of claim 1, wherein the crosslinkedextracellular matrix contains at least one of adenoviral vectors used ingene transfer and retroviral vectors used in gene transfer and plasmidsused in gene transfer.
 23. The implantable device of claim 1, whereinthe crosslinked extracellular matrix contains DNA used in plasmid genetransfer.
 24. The implantable device of claim 1, wherein the crosslinkedextracellular matrix contains protein.
 25. The implantable device ofclaim 1, wherein the crosslinked extracellular matrix contains RNA. 26.The implantable device of claim 1, wherein the crosslinked extracellularmatrix contains a viral vector.
 27. The implantable device of claim 1,wherein the crosslinked extracellular matrix contains an antimicrobialagent.
 28. The implantable device of claim 1, wherein the crosslinkedextracellular matrix is crosslinked with fibronectin.